Report: Philip Rivers playing through significant back injury

San Diego Chargers quarterback Philip Rivers' play has tailed off over the past six weeks, and the Chargers' playoff chances are hanging by a thread as a result, leading some to question whether Rivers is playing hurt.

ESPN's Adam Schefter says that's the case. According to Schefter, Rivers is playing through a back injury that is "bigger than people realize."

Rivers is also believed to be battling a rib injury, though ESPN's Eric Williams says the back is a bigger concern.

The Chargers went 5-1 to open the season, with Rivers posting a passer rating over 120 in five games. Since then, the Chargers are 3-5 and Rivers has topped the 100 passer rating mark only once.