For the purposes of keeping this post at a readable length, we'll be focusing only on the "starting" free agents and not the guys that have spent the last few weeks on the bench.
Aubrayo Franklin, NT
Franklin has been the starting Nose Tackle for each of the San Diego Chargers first 3 games of the season. What we've quickly learned is that Franklin is downright dominant against the run, but not very effective as a pass rusher. That's still a useful skill, and with Cam Thomas (who can rush the passer) behind him on the depth chart, the Chargers can take their time bringing Antonio Garay back from injury.
#90 / Defensive Tackle / San Diego Chargers
Sep 27, 1980
Former Team: Saints
Le'Ron McClain, FB
McClain's use to this team is similar to that of Jackie Battle's, another guy we'll touch on in a second. He's not much of a receiver and he's not much of a runner outside of typical power-back opportunities (Read: Goal-line carries). Even his blocking from the FB position has been suspect except for in the 4th quarter with a lead. McClain hasn't made anyone forget about Jacob Hester....yet.
#33 / Fullback / San Diego Chargers
Dec 27, 1984
Former Team: Chiefs
Jarret Johnson, OLB
Johnson, coming from the Baltimore Ravens, has been everything that he was billed to be. He's been very stout against the run and in coverage, and poor as a pass-rusher. He doesn't put up great numbers, he has just 5 tackles this season and no turnovers or sacks to speak of, but he has been responsible (along with Corey Liuget and Aubrayo Franklin) for the improvement in the San Diego run defense.
#96 / Linebacker / San Diego Chargers
Aug 14, 1981
Former Team: Ravens
Jared Gaither, OT and Nick Hardwick, C
Despite the fact that both of these guys were with the Chargers in 2011, they were both unrestricted free agents that the Chargers needed to sign to bring back. That's pretty much where the similarities end.
Nick Hardwick looks to be in the prime of his career, and might be the best Center in the NFL. If the Chargers can make it into the playoffs in 2012, this should be the year that he finally returns to the Pro Bowl (for the first time since 2006).
Jared Gaither looks to be in the prime of his retirement. After getting signed to a big contract in the offseason, Gaither has given the Chargers about a practice and a half and has spent the rest of this season in the trainer's room or on his couch. Coaches, media members and teammates are starting to grumble about Gaither's inability to play through injuries in a more public manner. This situation is weeks away from either a return from Jared or a drastic roster move from the Bolts.
#78 / Offensive Tackle / San Diego Chargers
Mar 18, 1986
Former Team: N/A
#61 / Center / San Diego Chargers
Sep 02, 1981
Former Team: N/A
Jackie Battle, RB and Ronnie Brown, RB
A.J. Smith signed Brown and Battle to fill the holes left in the passing game and running game by the departure of Darren Sproles in 2011 and Mike Tolbert in 2012. It also didn't hurt their chances of making the roster when Ryan Mathews broke his clavicle in Week 1 of the preseason.
Thus far, Ronnie Brown went from training camp star to regular season dud. Curtis Brinkley stole his spot as the starting RB with Mathews out, and seemingly stole the 3rd Down Running Back role from him in the process. Brown was inactive for the Falcons game and should expect to stay inactive until there's another injury to a Chargers running back.
Battle made the team on the strength of his Special Teams play, and because he was viewed as the only "power back" on the roster after Le'Ron McClain. Those guys are important for running the clock out in the 2nd half, as Battle made evident in the Titans game. All Jackie has done is impressed the fans, coaching staff and his teammates every time he's touched the ball (which isn't much). I'd be surprised if he doesn't end the year on the roster.
#44 / Running Back / San Diego Chargers
Oct 01, 1983
Former Team: Chiefs
#30 / Running Back / San Diego Chargers
Dec 12, 1981
Former Team: Eagles
Atari Bigby, SS
I still don't know how this is working. Bigby hasn't been a starter in the NFL in years because he can't stay healthy, so a team that administers massages to its players using chainsaws (probably) signs him and suddenly he's healthy and flying around the field like a 25 year old. Unbelievable. If Bigby can stay healthy, he might be the best free agent signing of the year....for any team.
#26 / Strong Safety / San Diego Chargers
Sep 19, 1981
Former Team: Seahawks
Robert Meachem, WR and Eddie Royal, WR
These were the two signings that got the most coverage for San Diego this offseason. These guys were signed to fill the hole left by Vincent Jackson, and eventually were counted on to also fill the hole (temporarily) left by the injury to Vincent Brown. So far, things have been.....okay.
Royal, much like his time with the Broncos, looks like a weapon that Norv can't quite figure out how to use. In each of the first 3 games of the season, Royal has caught 2 passes. However, he's averaging a disgustingly-low 4.8 yards per catch. He actually better at rushing, where he has picked up 7.3 yards per carry after running the ball 3 times.
Meachem, on the other hand, just seems lost. It's fairly obvious that the physical gifts are there: the size, hands, speed and toughness. However, him and Philip Rivers always seem to be making different reads, and Robert just seems very uncomfortable. Hopefully, things can get better in time, but Charger fans should prepare themselves to eventually hear that Meachem was simply a "bad fit" for this offensive scheme.
#12 / Wide Receiver / San Diego Chargers
Sep 28, 1984
Former Team: Chiefs
#11 / Wide Receiver / San Diego Chargers
May 21, 1986
Former Team: Broncos