Rex Ryan begins second shot at getting his defense to work in Buffalo

Will Bills learn Rex Ryan's defense? (1:33)

ESPN Bills reporter Mike Rodak talks about what the Bills' defense needs to do during their offseason program in order to be effective in Rex Ryan's system this upcoming season. (1:33)

Free agency, the combine and the owners meetings are in the rearview mirror, and the draft is just a few days away. But it’s time to get back to football on the field. Here’s a quick look at the Buffalo Bills as they open their offseason workout program Monday:

Biggest challenge facing head coach Rex Ryan: There is little doubt that Ryan needs to get his defensive scheme to work with the players he'll have this season. It's been a heavily discussed topic, but the point remains the same: Players did not buy in to Ryan's scheme and philosophy as well as he would have hoped last season. The result: the 19th-ranked defense that was mediocre against the run and largely ineffective against the pass. Ryan brought in his brother, Rob Ryan, and one of his former stars, Ed Reed, to help translate his system to players, but so far, he has lost more defensive talent than he has gained. It will be an uphill battle, and it starts in the classroom this spring.

Player on the rise: WR Sammy Watkins. Ask NFL fans nationwide to name the game's top receivers and there's a strong bet that Antonio Brown, Odell Beckham Jr. and Julio Jones will be some of the most popular answers. They've all been spectacular. Watkins can be, too; he just has to stay healthy. He spent last offseason rehabbing from hip surgery and then was limited significantly in training camp by glute and hamstring issues. After recovering from early-season calf and ankle injuries in 2015, Watkins eclipsed 100 receiving yards four times in the Bills' final six games. He's capable of that elite-level play on a more consistent basis if he doesn't get injured again, and fans around the country will take notice.

Player who has the most to prove: QB Tyrod Taylor. This might not be the most obvious choice because Taylor did plenty to prove himself last season, but he must do more this season. Entering his contract year, there could be tens of millions of dollars at stake in how he performs this season. Should Taylor answer questions about his abilities as a passer -- he never eclipsed 300 passing yards in a game last season and never won a game when he threw more than 30 times -- then he'll be in for a big payday, either through the franchise tag or a long-term extension. If Taylor doesn't make progress or takes a step backward, teams will be more hesitant to give him that monster deal.

Surprise player to watch: DE Jarius Wynn. I'll go outside the box on this one. Wynn missed all of last season with a torn ACL, yet he was an effective rotational player in Jim Schwartz's defense in 2014. Wynn has experience playing in a 3-4 system in both Green Bay and San Diego, and he's also a fit into a 4-3 system as a defensive end. He could be a player whom Rex and Rob Ryan use in multiple roles, and with Mario Williams no longer around, the Bills could use the help along their defensive line.

Position that should be addressed in draft: The defensive front seven. I get the sense that Bills fans would be happy if the team selected a big defensive tackle, a pass-rushing defensive end or a linebacker with their first-round pick. The team needs help at all three spots and there should be quality players available at any of those positions. How Rex Ryan sees players fitting into his system and how the first 18 picks shake out might determine who gets selected at No. 19.