1. WR Buster Davis -- The stars are aligned for Davis to have a big season. Here's a quick look at the facts: 1) he is entering his third season, a year when many receivers get comfortable in their transition from college to the NFL; 2) he is in the best physical condition of his career thanks to rigorous rehab and prehab; and 3) he is playing with a QB, Philip Rivers, who is emerging as one of the league's premier players.
Davis will be given every opportunity to nail down the slot receiver position, since Vincent Jackson, Chris Chambers and Malcom Floyd are all more comfortable outside the hashes. If Davis can stay healthy and grow into his niche, he could more than double his current career totals in receptions (24) and receiving yards (247).
FB Jacob Hester
2. FB Jacob Hester -- Hester was overwhelmed last season. As part of his transition from LSU to the NFL, Hester was learning to play halfback and fullback while also working on every special-teams unit. And while he made a sizable impact on special teams, his contributions on offense were limited because of his undefined role.
This season, Hester will be the unchallenged starter at fullback. He is 20 pounds heavier and 10 times more confident in his assignments. That should allow him to master one position and maximize his impact.
"There's a point where you can get too big and too stiff, and that's when you have to back off a little bit," Hester said. "It's a tough balance, trying to find that ideal weight where you can be versatile and effective."
3. LT Marcus McNeill -- It's tough to label McNeill a breakout candidate, since he earned Pro Bowl invites after two of his first three seasons. However, his play has been inconsistent over the last two years, making 2009 a pivotal campaign as he enters the final season of his rookie contract.
McNeill has a lot of questions to answer. Can he come back at 100 percent after offseason neck surgery? Can he cut down on his sacks allowed (12.5 over the last two seasons)? And can he inject some life back into the running game? If the answers to those questions are all "yes," McNeill can catapult himself into the top-tier of offensive tackles. If not, his future with the Chargers will be in jeopardy.
FS Eric Weddle
4. FS Eric Weddle -- Weddle had an up-and-down performance in his first season as a full-time starter. He led the team with 127 total tackles, yet gave up too many big plays in coverage; most notably, he yielded game-winning scores in Weeks 1 and 2 against the Carolina Panthers and Denver Broncos, respectively.
Nonetheless, Weddle responded well to Ron Rivera's promotion to defensive coordinator and played better over the second half of the season. And now that Rivera has had a full offseason to implement his playbook, Weddle should showcase his versatile skill-set more often, especially by rushing the passer.
5. LB Brandon Siler -- Siler continues to increase his role with the team. As a rookie in 2007, he made his impact by registering 21 tackles in kick coverage. Last season, he was again dominant covering kicks (16 tackles) while also shining in goal-line situations. This season, with the inside linebacker position in flux, Siler is eager to earn even more opportunities.
Siler is an aggressive defender who excels playing downhill. He will likely jockey with Tim Dobbins for the right to play opposite Stephen Cooper in running situations, leaving Matt Wilhelm and Kevin Burnett to scrap for time in the nickel defense.
Which Chargers players will break out in 2009? Talk about it in the message boards.
Michael Lombardo is a member of the Pro Football Writers of America and a long-time contributor to the Scout.com network. His analysis has been published by the NFL Network, Fox Sports and MySpace Sports. He has followed the Chargers for more than 15 years and covered the team since 2003.