He just re-signed with them. He was their #3 last year.
Chargers | Feeley contract details
Wed, 15 Feb 2006 15:41:03 -0800
Updating an earlier report, John Clayton, of ESPN.com, reports the restructured contract signed by San Diego Chargers QB A.J. Feeley was a two-year, $2 million deal that includes a $455,000 signing bonus.
I think they just re-signed him because they wanted a vet at #2 if Brees' shoulder wasn't ready by next season. They could hand the reigns over to Feeley if Rivers were to be absolutely horrid or if Rivers weren't there

...until Brees was 100%.