I agree it can be challenging, but I'm going to try to give a constructive reply.
The thing with the A.I. is, the first few pitches of an at bat, and of the game, dictate what the pitch mix is going to be going forward. If you chase one out of the zone early, you can expect to be a marked man and delivered a majority of balls the rest of the way, and, this is important, on any REPEAT tries for that moment, and every consecutive at bat going forward. This is why if you quit out and comeback later, you almost always have an easier time than you did when the CPU gave you everything in the dirt.
Also, certain pitchers are "junk ball" pitchers, at least as far as the game is coded, and some are low ball pitchers, some high, some have flat fastballs, and some break down, etc.
Anyway, if you chase early or at all, expect a sh^t show and quit out if it gets really bad and is trying you patience, and try to see what that particular pitcher is throwing that is causing you to chase.
I'm mediocre at the game, but have finished every moment, and though some are harder than others, I have a very good grasp on what the A.I. is trying to do. I hope this helps and don't get too discouraged!