to be honest i continually have this problem. i then tried MVP and hit a few for a while but the CPU was hitting too many corners with 70 mph changes after a 98 mph fast ball (i am in season 4). so i went back to all star with the following.
pitch speed - 25
user contact = 20
user power = 50
cpu contact 21
cpu power = 8
most of my game are like 6-4 or 7-3, etc. this, to me, is similiar to most games. most guys think that 2-1 is the norm. but look at today's scores. most are quite high scoring.
but even so, with the lower pitch speed the ball does not go as far. and the slow stuff is really tough. i doubt i have ever hit a HR off a change. but at least the FB is not blistering. in later seasons you get a lot of guys throwing high ninties with 70 changes. very tough.