Danario Alexander, a wide receiver who had emerged as a rising star in the back end of the previous season, had just torn his ACL in practice.
Floyd lasted two weeks into the season before a neck injury sent him to injured reserve. Brown has failed to make the expected impact. Allen has thrived, playing a major role in Philip Rivers' career resurgence.
"Keenan has gotten better every week," coach Mike McCoy said, via U-T San Diego. "And we've talked about it every week with him about continuing to build and taking it one day at a time. ... The kid's learning to be a pro, and he'll tell you that he has a long way to go. There are other things he can clean up, but he's done a great job."