My 11 years old son, is a pretty good pitcher but for some reason this year his balls are up in the strike zone, last night he got hammered. He pitches worse when he tries to aim the ball. Any suggestions.
Let him try working with a two-seam fastball. That pitch is also known as a sinker, and very often pitchers who have trouble with the four-seamer will do much better with the two-seamer, simply because that pitch will break downward. There was a case when National league pitcher Jim Brosnan, when he was with the St. Louis Cardinals back in 1959, was complaining to pitching coach Clyde King about his two fast balls, neither of which was working for him. King called in a catcher, had Brosnan throw for ten or fifteen minutes using both pitches, and then told him to drop the four-seamer and go with the two-seamer which was working much better for him. Brosnan became a sinker-slider pitcher and had a great deal of success with that combination over the next several seasons. 8)
Aiming the ball always ends up with bad pitches, I would consider that if he is leaving the ball up this could be because of a balance issue or that he might not be getting flat at the end of the delivery. Best thing would be get some video and upload them for us to have a look.
Check to see where their release is? Are they releasing out in front of the front foot or are they releasing closer to their head? Should be out front. Are they striding long enough? Too short a stride can result in a high release point and subsequent pitch high in the zone. If the stride is pretty short I would adjust that first as it may resolve the other as well. If they are striding ok - then make sure they are bringing their chest forward to their front knee ending in a fairly flat back during release.