Why do football players aways say "you" when they mean "I"?

They're talking to themselves in their heads.

It's actually a common psychological technique. When a person refers to him or herself in the third- or second- person point of view, it allows them to step outside of themselves, and "critique" themselves as a person through their own eyes. It allows them to assess what they need to work on by looking at themselves as if their consciousness and their own person were two separate beings. Think of it this way, when a professor tells you that your work/essay/piece must be peer-edited for you to receive full credit, they are telling you to let someone on the "outside" critique it. Your peers see you through outside eyes, as well as your work. They can tell you most what needs fine-tuning because they witness it first hand, with a non-biased opinion no less, as they have no attachment to the object in question. This exercise allows you to ,in essence, become your own peer, critic, and motivator.

The only player on the team that can be sacked is the quarterback. It is only considered a sack when the quarterback is tackled with the ball behind the line of scrimmage.

They probably skipped a few English classes as well.....