Can Youkilis keep up his hot streak?

Hey there, gang! Brendan Roberts is getting a well-deserved day off today, but he asked me to fill in as Grandmaster of the Hit Parade and give you my take on where the rest of the season should take you.

As you well know, correctly predicting the future performance of baseball players is crucial to fantasy baseball success. Take the incredibly strong early-season starts of second basemen Aaron Hill and Ian Kinsler, for example. If another owner offered you Alberto Callaspo straight up for either of them right now, would you pull the trigger on the deal? It's questions like that one which fantasy baseball owners have to make decisions about each and every day. Sometimes you'll be right, and sometimes you'll be wrong. If you can more accurately forecast which players on the statistical leaderboards have overreached their grasps and which ones have found firm footing for the future, you'll be in a far better position than your peers to take advantage of the "buy lows" and "sell highs" that title-winning fantasy owners rely on for their success.

So, you see a player like Kevin Youkilis hit .400 for almost a month. How does that translate into what kind of stats we can reasonably expect from him going forward? Since he is a career.294 hitter, some people will assume that means he's due for a lengthy cold streak in order to bring his average back down to his traditional performance level, therefore he should be benched or traded as soon as possible. Others will argue that "you always play the hot hand." Youkilis is riding high right now, and clearly is "in the zone." Therefore, there's no way you take him out of your lineup, as successfully as he's hitting the ball right now. Since they can't both be right, which camp should you listen to?

This is where you're most likely to hear the phrase "gambler's fallacy" tossed around. In a nutshell, the gambler's fallacy is the mistaken belief that recent events can influence the likelihood of future events. For example, if you're betting on whether a coin will come up heads or tails, and the past 15 tosses have all been tails, your instinct may be to believe that heads is "due." After all, what are the odds that 16 straight tails come up? Astronomical, right? And therein lies the fallacy, for regardless of what has happened in the past, the next toss is an independent event, and the coin still has a 50-50 chance of coming up heads. No more, no less.

But this analogy doesn't quite translate into baseball. Every time Youkilis, or any other hitter for that matter, comes to the plate, the probability of getting a hit is not fixed. The odds can change based upon the type of pitcher he's facing, where the game is taking place, the weather, whether or not there are runners on base, the pitch count as the at-bat progresses, the score of the game, whether or not Youk is feeling particularly confident or not … there's an infinite number of variables that enter into the equation. So while perhaps the fact that hitting .400 for the season is an extremely rare feat, there's nothing that precludes Youkilis from accomplishing it from this point forward, and it's truly just as likely for him to hit .100 for the rest of the year as .200 or .300, from a probability point of view. It's this real world uncertainty that makes fantasy baseball such a challenge.

That does not mean you can't make an educated guess on whether or not a player has truly elevated his game to a new level or has just gotten extremely lucky for a month of at-bats. Sure, the ESPN Player Rater -- as well as other systems like it -- does a fairly good job of attempting to compare how well each major league player has performed so far this season in relation to all the others. The problem with using the ESPN Player Rater as a predictive aid is that, well, it isn't one. This is because the ESPN Player Rater is strictly a comparative tool. The better you are in a given category than the "average player" earns you a higher rating. The problem with that methodology is that a player's value changes more based on the performance of others rather than the quality of his own skill set. For example, if Carl Crawford is the best base stealer in baseball, he should be valued as such, and not have that ability minimized by the fact that Jack Cust's one stolen base raised the league average, and therefore, deducted value from Crawford.

So for this week's "Stat Talk" section of Hit Parade, I've come up a brand-new stat called "mass and momentum": a ratings system that is both "value-based," as well as "skills-based" in order to create a way to indicate which players may have already peaked, and which ones still have the "momentum" to continue on their current pace.

More on Massmomentum

From Ian Kinsler all the way down to Jason Smith, AJ Mass ranks more than 400 players and their ability to maintain their current pace.
Click here to find out.

First, we'll assign each stat used in a standard 5x5 league a value based upon the total number of each that exists in the current major league universe so far in 2009. If there are fewer stolen bases than home runs by a factor of 1.6, then each individual stolen base will be worth 1.6 more than each home run in my rankings, and so on. (This is different from the ESPN Player Rater, where each statistical category is weighted equally.) This value is then averaged per at-bat and scaled out to the average number of at-bats for a regular everyday player, so that those with limited playing time do not get overvalued. We then rank the to-date accomplishments of each player to measure the speed at which he's accumulated his stats so far this season. We'll call this a player's "velocity."

Next, we take the velocity and tweak it according to a complex formula based on each hitter's skill set, determined by a combination of stats that measure patience at the plate, ability to put the ball in play, power potential and speed. This "weighing down" of the velocity creates a new value, called a player's "mass," and shows where each player's true rank should be, taking away any "lucky streaks" unwarranted by an analysis of the individual skills exhibited so far in 2009.

The last step for predicting future performance comes in combining the ranks of mass and velocity into a single stat called momentum. A number close to zero indicates that a player is performing exactly as expected so far in 2009. As the momentum gets more positive, the more likely it is that the player will be able not only to sustain his current numbers longer, but also to possibly improve upon them. And conversely, the more negative a player's momentum is, the more likely it is that the player's performance will come crashing back down to earth, unable to continue its ascent into the stratosphere.

I'll be using this as my basis for the analysis that follows, and I hope you'll come along for the ride. Fasten your seat belts … here we go!

Fortunes Rising

• Kevin Youkilis, 1B, Red Sox (mass of 17, momentum of 21): As we said earlier, people are going to be looking for reasons why Youkilis can't possibly keep his average at such a lofty level and scrambling to "sell high." But we think it's just the opposite here. He's not dropping to a .150 average to even things out and while his batting average will level out, his BB/K ratio has never been better and his power numbers suggest a continuation of his steady growth over the past four seasons.

Victor Martinez, C, Indians (mass of 8, momentum of 63): The 2008 season, which essentially amounted to a "year off" for V-Mart, did him a lot of good. He's hitting more line drives than at any point of his career and his HR/FB ratio has returned to the expected level of growth he should be at, had last season not been a washout due to injury. Plus, the extra time away from the catcher position is going to leave him far fresher as this season goes along.

• Alberto Callaspo, 2B, Royals (mass of 44, momentum of 97): The scary thing about Callaspo is that he's actually not hitting the ball all that well, with very few line drives. That just makes the 13 extra-base hits all the more impressive, and with his contact rate at more than 95 percent, the chances of him sustaining his early-season groove are about as high as you can get. So yes, we would trade him even up for Aaron Hill (mass of 4, momentum of 7), even though we don't think his start to 2009 is a fluke either.

Fortunes Falling

Curtis Granderson, OF, Tigers (mass of 24, momentum of -14): Don't get me wrong, Granderson is a terrific player who usually contributes in all five categories. But nine home runs in 108 at-bats? That's not a pace that suits his strengths. Granderson is hitting fly balls one out of every two times he puts the ball into play and those fly balls are clearing the fence at a ridiculous rate of 21.4 percent. This power just isn't sustainable if you're also looking for the batting average to come around.

Matt Kemp, OF, Dodgers (mass of 36, momentum of -23): Another solid player who has simply had the good fortune of everything falling his way early. His strikeout rate is extremely high, yet he's still averaging one RBI for every 1.6 base hits. That seems to be a rate of production that is more a result of his teammates' work than anything Kemp is doing on his own, and a huge dip in his RBI pace is all but assured going forward.

Dexter Fowler, OF, Rockies (mass of 97, momentum of -68): This is a simple case of a player's value being inflated by what essentially amounts to a standout single-game performance. Sure, Fowler is fast and will steal a lot of bases this season. That's only one category, however. He's still got a wild swing and chases far too many bad pitches, meaning he's not going to get on base enough to warrant keeping him around just for his speed. All the buzz around his five-steal game means you can get a lot of value for him now, before the other owners in your league start to see the slide that we've projected for Fowler.

Pickups of the week

Mixed: Casey Kotchman, 1B, Braves (mass of 147, momentum of 91, ESPN ownership of 25.4 percent): Home runs? Nope. Steals? Umm … no. That's why he's available in so many leagues, but if you're looking for a batting average boost, you've come to the right place. Kotchman has hit safely in 19 of 26 games through May 5.

AL-only: Jayson Nix, 2B, White Sox (mass of 338, momentum of 62, ESPN ownership of 0.1 percent): Now that he's healthy, he'll play infield and outfield and just enough to be useful as a spot starter in a deep league.

NL-only: Laynce Nix, OF, Reds (mass of 240, momentum of 57, ESPN ownership of 0.1 percent): Staying with the Nix clan, Laynce is not yet a starter in the Reds' outfield, but Dusty Baker told reporters he plans on playing him "enough to stay sharp."

Lineup Card

With Carlos Guillen off to the disabled list, Jim Leyland is using the opportunity to shake things up in his lineup. On Tuesday, he dropped Granderson to fifth in the order and inserted Josh Anderson in the leadoff spot. He also dropped slumping Magglio Ordonez from third to sixth, the first time he's hit that low in more than a decade. Whether it's a permanent change, or just a short-term experiment to shake things up remains to be seen, but the 9-0 win on Tuesday certainly bodes well for this current lineup's future effectiveness if it remains intact.

On the farm

Shelley Duncan, OF, Yankees: He's tearing up Triple-A with 10 home runs for Scranton/Wilkes-Barre to go along with a .333 batting average. Now if only Nick Swisher would stop hitting so he might get a chance at a call-up.

• Jesus Guzman, 3B, Giants: Guzman is hitting a blistering .415 over his past 10 games for Triple-A Fresno, and is hitting .364 with runners in scoring position on the year. With Travis Ishikawa struggling, perhaps San Francisco might want to move Pablo Sandoval to first base and bring up Guzman?

Final thoughts

Every so often we get a suspended game like the one between the Nationals and Astros on Tuesday, and it's important to learn your league's rules on when -- or even if -- these stats count for your fantasy team. For example, in most cases, Elijah Dukes' two home runs should go into effect right now, even though the game won't finish up until July 9. However, it's important to realize that if you play in a head-to-head league, when July 9 does roll around, any further stats for the players in this game may not actually count for you. Major League Baseball will credit those stats back to the start date of the game, and by then most fantasy leagues will have already locked the results. Just something to straighten out today, before Dukes wins the game with another homer in the bottom of the 12th inning two months from now.

AJ Mass is a fantasy baseball, football and college basketball analyst for ESPN.com. You can e-mail him here.