I'm sympathetic to the comments about being limited by the scheme, but let's be honest, there isn't a single coverage scheme that involves NOT teaching guys to turn around and look for the ball when it's in the air.
It's one thing when you're just beat and trying to catch up, but I couldn't believe the number of times last year guys had decent position and then got flagged for PI or didn't make a good play on the ball because they just didn't turn the head around. As a former cornerback that just kills me.
Now, not being a fly on the wall in practice, I can't say whether that's a coaching problem (and if it is, whose problem) or if it's just a lack of execution on the players' part. But I would sure like to see a lot less of it this year.