The Chargers are arguably worse than their record (4-6) would suggest. The driving force behind that mediocrity has been the offense, so today we'll stay focused there. I know there has been plenty of disappointment to be found on the other side of the ball as well, but that's a question for another day.
It's difficult to know where to start as there are just so many choices. Jared Gaither, that malingerer, seems like the obvious choice, though. Signed last year as a street free agent in the middle of the season, Gaither was mistaken for the savior of the Chargers offensive line. He came in during the week and was starting that weekend. The line quickly gelled and the team got on a roll winning enough games to finish with a winning record. He then signed a big free agent contract to be the starting left tackle for the foreseeable future. That has not worked out so well. He's been unable to get on the field and when he has made it his pass blocking hasn't been as good as it was last year.
Robert Meachem, signed to a big free agent deal this past off season, has been mostly healthy all season. He's just been a complete non-factor. At times it seemed like he didn't know where he was supposed to go. The Chargers offense relies heavily on option routes and it can take time to adjust as a receiver that previously only ran a handful of routes as a professional. However, there were also times where he simply wouldn't fight for the ball and he's since been replaced as the starter by street free agent Danario Alexander.
Another high profile signing this Spring was fullback Le'Ron McClain. He was supposed to open up huge holes for Ryan Mathews (who has never experienced running through huge holes as a pro) to run through. He was also supposed to be a weapon carrying and catching the ball. He has done none of those things as a Charger. He has done very little with the ball in his hands and his run blocking has almost been enough to make you miss Jacob Hester.
Finally, there's El Capitan himself, Philip Rivers. After a slow start in 2011, Rivers caught fire and finished the year as a top 10 quarterback statistically and nearly willed the Chargers to the playoffs. In 2012, Rivers has simply been terrible (by his standards). He's actually been very average, but when the whole team is built around the idea that you're an elite passer, average might as well be terrible. Now, some of the blame has to fall on his offensive line and his receivers, but so many of Rivers' turnovers have been unforced errors, that it's impossible not to point the finger at him as well.
Anyway, vote in the poll (I've added a couple other names I've heard thrown around as well) and let us know if we missed anyone.