SAN DIEGO -- The San Diego Chargers have placed wide receiver Keenan Allen on season-ending injured reserve with what's believed to be a torn ACL in his right knee, and activated rookie Joey Bosa a day after a stunning loss at Kansas City.
Allen injured his right knee in the first half of Sunday's 33-27 loss in which the Chargers blew a 21-point, third-quarter lead.
Bosa has been on the roster-exempt list. He missed all of training camp in a nasty contract dispute and then tweaked a hamstring last week. Coach Mike McCoy said he doesn't know when Bosa will be ready to play.
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McCoy had few explanations for Sunday's meltdown, other than repeatedly saying it was a lack of execution.
The Chargers have lost nine straight AFC West games dating to 2014.