I would guess to help with the CPU completion percentage. I put my CPU's passing slider all the way, but had to put it down after a CPU's third string QB - with a throwing power in the 70s - was throwing the ball 70 yards in the air. I've since put it down a bit, but higher than default. Their completion percentage is still lower than I'd like though. I'll probably need to turn down my awareness a bit more as well.