Primarily that's going to be Pass D Reaction slider, and probably Coverage impacts that a bit as well as your zone defenders will be in better position to begin with.
PDRT is not a 'sensitive' slider, so if you dislike how it's playing now, I'd crank it way way up.
Unfortunately I wouldn't expect it to affect deep blue zones too much. They patched the game a while back and deep blue coverage became semi useless once again. It's a shame because it was sooo good in the beta & right @ release. If a receiver was the only deep route, that deep blue defender would 'attack' the route rather than just drop senselessly to nowhere.