The Chargers have a rich tradition of undrafted free agents not only making the 53-man roster but eventually developing into impact players. San Diego has several UFAs in camp who show promise. Perhaps one of them may turn out to be a future Pro Bowler -- like TE Antonio Gates.

Five undrafted free agents to watch in preseason

CB Greg Gatson (Arkansas): Gatson has frequently received praise from secondary coach Ron Meeks. He has naturally strong coverage skills and appears extremely coachable. Gatson is a long shot to make the 53-man roster, but easily could stick around on the practice squad.

LT Mike Harris (UCLA): QB Philip Rivers said Harris has seen more snaps with the starters in his first training camp than probably any other undrafted LT in NFL history. LT Jared Gaither (back spasms) and backup G-T Brandyn Dombrowski (foot, cyst) are not practicing. Harris has had mixed performances in practice. Thursday’s game against the Packers will be a big test for him.

RB Micheal Hayes (Houston): Hayes, 5-8, 200, looks like a thick RB Darren Sproles when he is carrying the ball. Hayes could be one of the most exciting players to watch in preseason. He has repeatedly evaded tacklers and broken off long runs in practice.  Hayes is likely competing against RB Edwin Baker (round seven, 250th overall pick) for a spot on the practice squad.

QB Jarret Lee (LSU): Lee will come into the first preseason game as the second-string QB because QB Charlie Whitehurst (sore MCL) will not play and newly signed QB Kevin O’Connell does not yet appear confident. Lee did not impress through the offseason workouts and early in camp, but has looked significantly better in recent practices.

WR Mike Willie (Arizona State): Willie, 6-2, 200, impressed in minicamp and has shown flashes he can play throughout training camp. Willie will play late in preseason games and will l receive an opportunity to impress. Willie is also likely competing to be on the practice squad because the Chargers are deep at WR.

Follow Chargers reporter Dan McLellan on Twitter @CBSSportsNFLSD and @sandiegosports.