Sizing up the top free agents for 2015

The NFL free-agent market will open next month, ushering in the league's annually illogical frenzy for players deemed expendable by their incumbent teams. At the moment, of course, we can only guess at the details. Who will be available? How much cap space will teams have? Which owners with authorize significant spending?

Those questions are under review in most NFL cities, to be determined over the next 26 days heading toward the March 10 opening bell. What we're left with now is a really deep -- but largely fantastical -- 2015 class. Many of its members will re-sign in the coming weeks. Some will be given the franchise tag as early as Monday. A few will make it to the open market, where teams salivating for a big-play receiver or an established pass-rusher will be waiting.

So while we have a chance, let's have some fun and consider the possibilities. What follows are arguably the 20 best players whose contracts are set to expire on March 10. (This does not include players who will be released in the coming weeks.) Theoretically, it's a monster class that includes the NFL's top rusher in 2014, its leader in receiving touchdowns and its most productive pass-rusher. Realistically, it's a reminder of the intense work left to be done for some teams and a glimpse at the big picture for the rest.

Thanks to ESPN scout Matt Williamson, who provided insight on each player and guidance with the rankings, and ESPN Stats & Information for some of the statistics and the salary-cap information. The chart at the bottom of this story displays the salary-cap space available to each team as of earlier this week, based on a (likely low) estimate of $140 million cap per team. The numbers will change often in the coming weeks, but if nothing else, they provide a sense for which teams need to make adjustments for an active foray into free agency.

1. Ndamukong Suh, DT, Detroit Lions

One-liner: Retaining Suh via the franchise tag would cost $26.7 million in cash and cap space, a presumably prohibitive total, but team president Tom Lewand has said the Lions have a "very, very good chance" of signing him to a new multiyear deal.

Williamson's report: "He's one of the few defensive players that make everyone around him better. He demands attention. He can fit any scheme. You can use him like J.J. Watt as a 3-4 attacking defensive end or certainly as a tackle in the 4-3. He's the type of player that anyone who runs any scheme would want."

Stat to note: Suh is a three-time All-Pro in five seasons whose 36 sacks leads all NFL defensive tackles over that period, a statistic that only begins to describe his value.

2. Dez Bryant, WR, Dallas Cowboys

One-liner: Despite a tight salary-cap situation, it's difficult to imagine the Cowboys parting ways with their top game-changer after he set a franchise record for touchdown receptions in a season (16).

Williamson's report: "He has improved dramatically with his route running, route recognition and the smaller things of the game. Of course, in the back of your head, you're asking if you're comfortable giving him a huge pile of guaranteed money. He's had some behavior stuff. But he sure seems much improved off the field and much more mature."

Stat to note: Since free agency began in 1992, only one receiver has opened a season with a new team the year after leading the NFL in touchdown receptions. That came in 2005, when Muhsin Muhammad was released by the Carolina Panthers and signed with the Chicago Bears.

3. Justin Houston, LB, Kansas City Chiefs

One-liner: Here's the litany of the nine other men to record at least 20 sacks in a season: Five are in the Hall of Fame, three are still active and the other is Mark Gastineau.

Williamson's report: "If I had to pick one edge pass-rusher, it would be Houston. I think he's the best in the league. Speed and everything else. And he's really getting better and better each year. Just highly productive and never comes off the field."

Stat to note: The NFL made the sack an official statistic in 1982. Since then, only two players have led the league in sacks and then started the following season with a new team. The Panthers released Kevin Greene after the 1996 season, and the Chiefs traded Jared Allen in 2005.

4. Demaryius Thomas, WR, Denver Broncos

One-liner: It's fair to wonder how the success of 2014 free-agent acquisition Emmanuel Sanders, whose 1,404-yard season in Denver doubled his 2013 output in Pittsburgh, could impact negotiations with Thomas.

Williamson's report: "He's got superstar ability and obviously is great after the catch. I think he would be highly productive in every system, but he does benefit from those around him. That's why I think he's a slight tick behind guys like Julio Jones, A.J. Green and Dez Bryant, but not by much."

Stat to note: Thomas is big and fast but isn't simply a deep threat. He has led the NFL in yards after the catch (1,874) in the past three seasons.

5. Devin McCourty, S, New England Patriots

One-liner: The 2014 free-agent contracts secured by Jairus Byrd (New Orleans Saints) and T.J. Ward (Denver Broncos), as well as the market-level deals signed by the Seattle Seahawks' duo of Earl Thomas and Kam Chancellor, point toward a high value for McCourty if the New England Patriots let him hit the market.

Williamson's report: "I'd be shocked if the Patriots let him go. He came into the league as a first-round corner. He's a really good cover guy as a safety. He can play deep center field. He spied on Russell Wilson in the Super Bowl. He can play man coverage versus tight ends and then move to single-high. He's exactly what [Patriots coach] Bill Belichick wants.'"

Stat to note: McCourty isn't a flashy playmaker in the Patriots' scheme, but his balance as an all-around player is evident. Pro Football Focus credited McCourty with 21 tackles, and just two missed tackles, against the run in 2014.

6. Randall Cobb, WR, Green Bay Packers

One-liner: It's puzzling to consider why the Packers would part ways with Cobb, a model citizen who had career highs in yards (1,287) and touchdowns (12) last season -- unless it's a concern about paying him more than the $9.75 million annual average of teammate Jordy Nelson.

Williamson's report: "I like Cobb a lot, but he worries me a little bit. I don't know that he's the guy that can deal every week with facing the best cover guys. He can do a lot of things, but is he that guy? I don't know. He is great in the slot and can make a lot of plays, but he's not a burner. The Packers have a pretty good package for him. You can't assume he's just going to produce on any team he's on."

Stat to note: A college quarterback, Cobb is a good route runner but is best known for making plays on his own as well. The Packers have given him 27 carries out of the backfield in his career, and over that span, he ranks fifth among all NFL receivers with an average of 6.19 yards gained after the catch.

7. Julius Thomas, TE, Denver Broncos

One-liner: Although Thomas hasn't had so much as an 800-yard season, and has missed five games with assorted injuries in the past two years, he has been enormously productive from a scoring standpoint: 24 touchdown receptions in 27 games.

Williamson's report: "I think he's a very good athlete, but not an elite athlete. I don't know that he has a Jimmy Graham-type of ceiling. You do look at what happened to the Broncos' offense after he got hurt last season. It was much worse. They went to the run. A lot of people said that was because of Peyton Manning, but another big reason was this guy was out. They lost that red zone production. But if he goes to, say, Jacksonville and is the top receiver on that team, I could see him really taken away by defenses. There is some 'buyer beware' there, to me, in terms of a guy where his stats are great but then, depending on his next home, could fall off in a big way."

Stat to note: The Broncos targeted Thomas 15 times in the red zone in 2014. He caught 13 of them (86.7 percent), including nine for touchdowns.

8. Jason Pierre-Paul, DE, New York Giants

One-liner: As the Giants know better than anyone, Pierre-Paul has been a boom-or-bust player with a serious 2013 back injury already in his medical files.

Williamson's report: "He's a tough one for me. I don't know that he's quite good enough to be a guy you franchise, but he has been elite at times in his career. He's become more well rounded and better against the run, but is he a guy you're really frightened of? I don't always know what to think of him. You've seen him do it, seen the ability, but he's had some injuries, and you're making a big projection to assume he can get back to when he was at his absolute best."

Stat to note: Pierre-Paul has twice exceeded 12 sacks in a season. He's finished below seven sacks in each of his other three seasons.

9. Pernell McPhee, DE, Baltimore Ravens

One-liner: McPhee has started six games in four years, but his well-timed sacks in 2014 have him poised for a significant payday.

Williamson's report: "This isn't a well-known player, but he's a highly versatile guy. He can be a 3-4 outside linebacker, or you can align him all over the formation. Every time he's on the field, he makes a lot of plays. As a pass-rusher, or whether he's asked to be stout against the run, he's really played well. But he was still a bit of a part-time player. The Ravens have Terrell Suggs and Courtney Upshaw, and they had to find ways to get him out there. The question is, does he become Paul Kruger and fall away to nothing if he leaves the situation and is being counted on to be the man?"

Stat to note: McPhee had 7.5 sacks while playing less than half of the Ravens' defensive snaps in 2014. He played 489 snaps. For comparison, inside linebacker C.J. Mosley played a team-high 1,019 defensive snaps.

10. Jerry Hughes, DE/LB, Buffalo Bills

One-liner: For the past two years, Hughes made opponents realize there was more than one edge rusher to account for on the Bills' defensive line.

Williamson's report: "I think a lot of people see Hughes doing well the past two years and say it's because he's playing with Mario Williams, and Williams commands all kinds of attention. There is some truth to that, but Hughes stands out on his own. When you watch the tape, it's not like everyone rolls their protection toward Mario on every play. Hughes is getting his, too. He'd be best in a 4-3 but could play linebacker in a 3-4. He started out as a bust in Indianapolis, but he's put it together, and you could get four really big years from him."

Stat to note: Hughes posted 10 sacks in 2013 and 2014, one of six players to hit double figures in each season. His 20 sacks since the start of the 2013 season quadrupled his total in three previous seasons with the Colts.

11. Bryan Bulaga, OL, Green Bay Packers

One-liner: After having his 2012 season cut short (hip) and missing all of 2013 (ACL), Bulaga returned to start 15 games in 2014.

Williamson's report: "He's not a flashy guy or player. If you're listing his strengths, you wouldn't have any that are off the chart. He's not an A-plus athlete and he doesn't have A-plus strength. But, really, there are no negatives. There's nothing that you would say, boy this is a massive weakness that might make you hesitate to pay him. He's not heavy-footed on the left side, and he doesn't have strength issues when he plays on the right. He's just a really solid starting offensive tackle. There's hardly any of them on the market this year, and I would think he would demand a lot of attention."

Stat to note: Bulaga's availability, and the subsequent consistency of the Packers' offensive line, led to a big year for the offense. It produced an NFL-high 170 total expected points added (EPA), an advanced analytic that quantifies performance compared to a league-wide average.

12. Mike Iupati, G, San Francisco 49ers

One-liner: The 49ers have been aggressive about adding offensive line depth in recent drafts, most notably drafting Brandon Thomas and Joe Looney, making it fair to wonder if they'll pass on devoting big resources to Iupati.

Williamson's report: "He really looks the part. He's got the attributes of a guard taken in the first round, for sure. He's massive and powerful but not really that fleet afoot, which makes him perfect for what [former 49ers coach] Jim Harbaugh wanted him to do there. I'm not sure he's the type of guard that you can plug into any system and be fine. He's a mauler, and moves well for a mauler, but he's still a mauler, and some teams need guys who can move better. I could easily name half a dozen guards in the league who are better. He is not elite."

Stat to note: Iupati's tenure with the 49ers began in 2010. Since then, the team has gained the NFL's third-most rushing yards (7,076) prior to contact.

13. Jeremy Maclin, WR, Philadelphia Eagles

One-liner: Maclin bet on himself after a 2013 ACL injury, turning down a five-year contract offer in favor of a one-year deal for what turned out to be an 85-catch, 10-touchdown season.

Williamson's report: "Maclin is a tough one. I wouldn't be super-excited about investing in him. He's a good player but not great. He's not a pure speed guy, but he's fast. He's not a 'possession guy,' but he can move the chains. But the way free agency works is that he's ultimately a No. 2 wideout who'll probably have a chance to be paid like a No. 1. He's a player everyone wants, and if you could put him across from Larry Fitzgerald or Andre Johnson in their primes, then now you're talking. If you have Andre Holmes on other side, well, he'll be a different guy."

Stat to note: Maclin was a workhorse in his first year back from the ACL injury. He participated in 980 offensive snaps, fourth most among NFL receivers, and was targeted 142 times -- the eighth-highest mark in the league.

14. Torrey Smith, WR, Baltimore Ravens

One-liner: Smith is one of the NFL's top deep threats, but his week-to-week production -- he has caught more than 50 passes in only one of his four seasons despite never missing a game -- makes it difficult to argue he is a No. 1 receiver.

Williamson's report: "I think he gets a bad rap as a one-trick pony, that he's a speed guy. For the most part, it's true, but it's a pretty good trick that he has. He scares the heck out of defenses. He's not a real skinny guy like a DeSean Jackson or Ted Ginn, two other big speed guys. He has meat on bones. He can break tackles and show some physicality and draw pass-interference calls. He has improved as a move-the-chains technician. He's not a true No. 1 receiver, but if you had a big physical guy on other side, like in Carolina with Kelvin Benjamin, you would get the most out of him."

Stat to note: Since the start of his career in 2011, Smith leads the NFL in average air yards per target (16.6), a strong measure of the frequency with which the Ravens used him on deep routes.

15. Byron Maxwell, DB, Seattle Seahawks

One-liner: Drafted one round after Richard Sherman in 2011, Maxwell started 17 games in the past two seasons but might be squeezed given the Seahawks' financial commitments to Richard Sherman, Earl Thomas and Kam Chancellor.

Williamson's report: "He's kind of like the receivers in this class who are a high-end No. 2s, in this case a corner. The Seahawks play a ton of Cover 3, and people don't throw to Sherman, so Maxwell sees a lot of attention. He handles it well, but I don't know that you want him to come down and press a No. 1 receiver all game or think he'll find a way to create some kind of Revis Island. He's not that guy, and few are. He moved into the slot in the Super Bowl, and that was a spot New England attacked. He'll make too much money in free agency, but he won't disappoint anyone. He'll be an above-average starting corner in any situation."

Stat to note: Of the 34 players who have intercepted at least six passes in the past two seasons, only four did it in fewer than Maxwell's 1,114 snaps.

16. DeMarco Murray, RB, Dallas Cowboys

One-liner: The last player to lead the NFL in rushing and start the following season with another team was Bill Dudley, who moved from the Pittsburgh Steelers to the Detroit Lions -- in 1947!

Williamson's report: "He's the biggest 'buyer beware' in the class for me. He was running behind the best line in the league, and there are all kinds of stats about guys who have seasons with that many touches and never get back. When you look at his season, he wasn't getting as many yards on his own at the end of year. He has that injury history. And if you're asking who is more talented, I could easily come up with six or eight other running backs. Adrian Peterson could have gotten another 500 yards in that situation."

Stat to note: Murray's first 16-game season led to 392 carries, making him one of nine running backs in NFL history to meet or exceed that total. All six of the most recent instances fell short of 1,000 yards in the following season.

17. Brian Orakpo, DE, Washington Redskins

One-liner: Orakpo's market value is unclear after a quad tear cost him 14 games in 2012 and an ACL injury knocked him out for the final nine games of 2014.

Williamson's report: "He's great when healthy. He's probably better in a 4-3 than a 3-4. Can he be a team's No. 1 pass-rusher and still produce? I would say Orakpo is a No. 2. He can be an unbelievable No. 2, but he isn't quite Justin Houston. You have to put an asterisk by him. What condition is he in? He hasn't played in a long time. But you like him a lot when he's on the field."

Stat to note: As a result of the injuries, Orakpo's suitors must deal with a stark deficiency of recent production. Nearly 72 percent of his career sacks (28.5 of 40) came before the 2012 season.

18. Brandon Graham, DE, Philadelphia Eagles

One-liner: A first-round pick in 2010, Graham got caught up in the Eagles' scheme shift to a 3-4 and has started only one game in the past two seasons.

Williamson's report: "He was drafted pretty early as a 4-3 end, and then the Eagles changed coaches and scheme and that hurt him. They signed Connor Barwin and all of a sudden Graham is a true backup, not even a rotational player. He was third on the list. When you watch the tape, you see that he's productive when on the field. He's out there, doing good things and he's making good plays. He adapted. But take a team with a 4-3, put his hand in the dirt, bring him off the edge on passing downs at a minimum and he'll get to the quarterback. He's got a skill everyone wants and everyone will pay for."

Stat to note: Graham made efficient use of his 482 snaps, which were roughly 43 percent of the Eagles' total defensive plays. In that span, he put up 5.5 sacks, 47 tackles and four forced fumbles.

19. Rodney Hudson, C, Kansas City Chiefs

One-liner: A second-round pick in 2011, Hudson has started 31 games in the past two seasons and plays a position with few starting-caliber options set to be available on the market.

Williamson's report: "He's a smaller, more athletic center and moves really, really well. He can bend, move out on screens and get to the second level. He was by far the best lineman on a bad line in Kansas City and consistently got better. Right now, I'd say he's knocking on the door as one of the top handfuls of centers in the league."

Stat to note: Because of injuries and poor play, a stunning 57 centers saw regular-season snaps in the NFL last season.

20. Greg Hardy, DE, Carolina Panthers

One-liner: Hardy might be a toxic asset, given his possible suspension and baggage connected with a since-overturned conviction for domestic violence, but NFL teams love pass-rushers and he is a good one.

Williamson's report: "If he's clean, he's the fifth- or sixth-best guy on this list. He's a pure 4-3 defensive end, not really a 3-4 guy, which limits some teams. But he can play the run and is just a really, really good player. He was certainly missed last year in Carolina. You have to ask yourself if he is the same guy, or if he's changed, and will he get in trouble again? But as a pure player, he was great for those two years."

Stat to note: Hardy recorded 26 sacks in 26 starts during the 2012-13 seasons. The only players with more during that period were J.J. Watt, Robert Quinn, Aldon Smith and Robert Mathis.