Although the two-time Special Teams Player of the Year award winner can make a huge impact chasing down kick returners, Polk's shoulder injury only highlighted his biggest issue- his durability.
In the past four seasons, Polk has missed 37 games due to injury. He was on the injured-reserve list again at the close of last season but is expected to return in healthy form. When in fit shape, the knowledgeable veteran affords depth at every linebacker position and greatly enhances the special teams.
LB Tim Dobbins
In Dobbins' defense, the two games he fielded in the temporary role were against Tom Brady and Brett Favre. Both quarterbacks managed to exploit Dobbins struggles in pass coverage, but he's hardly the first linebacker to fall victim to their precision passing.
Although Dobbins struggles in a supporting role on defense, he has amped up his game on special teams. He recorded 15 tackles in kick coverage last year, more than even Pro Bowler Kassim Osgood.
With the signing of 12-year veteran Derek Smith and Anthony Waters' return to health, the Chargers have only added to their already excessive inside linebacker depth. In order for Dobbins to see field time, he will have to prove an irreplaceable force on special teams…and that means outplaying Polk.
Stephen Cooper will not count against the roster while he is suspended for the first four games of the season due to a violation of the NFL's substance-abuse policy, which may leave a temporary place for both Polk and Dobbins. But upon Cooper's return, it's likely the loser of of this training camp battle will be traded or released.