Hi bballmom36,
I agree with the previous posts about having him practice his pitching motion 3 to 4 times a week. This will develop muscle memory. However, I would also look at these other areas:
1. Is concentration an issue for him? Can he focus in or does he get easily distracted when something wrong happens?
-if either is the case, you can have him practice visualization drills that allow him to concentrate better, move past errors more easily, and put him in the right mindset. Here, is an example of this:
Baseball Pitching Visualization Drill2. Is he in control of his delivery? Often times, a pitcher can have trouble with control b/c they have a balancing issue. To address this, he can either practice drills that improve his balance or simply his pitching windup to reduce any rocking or head movement in his delivery.
3. Consider getting a few pitching lessons from an experienced instructor. A good instructor will be able to pinpoint a few things right away and show him how to do it correctly. From here, his daily practicing would take over and he could help overcome his control issues.
Hope this helps,
Jack Elliott
Baseball Training Tips