High and inside fastballs are tough on the higher difficulties, especially if you play diamond dynasty and the high velocity reliever cards start getting released more frequently. As long as input lag isn't holding you back, it's a matter of getting in good counts and anticipating it. A lot of players' tendencies become pretty obvious over a 9 inning game. If you get 0-2, 1-2 too often you're kind of at their mercy.
One strategy I use when I'm struggling is I'll take until I get a strike (or at least take the first pitch one time through the order). 1) It'll force your opponent to throw strikes to beat you. If you're taking balls early in the game, they are less likely to expand the strikezone and they are more likely to make a mistake over the middle of the plate (also the pitcher's confidence meter won't get maxed out). 2) On the pitches you take, you can practice moving the PCI marker to the pitch. 3) Pitch counts.
Also use strikezone view if you aren't already.
I think that's actually my pitching K/9 all jacked up because of the DNFs. Sony's formula is screwy. I had a 22 K game the other day. Guy was literally swinging at everything and I didn't realize until like the 5th inning.