Lost location!

I just joined the forum and had a question for help.My 11 year old has had exceptional control till recently.Alot of his pitches are short of the plate and in the dirt.I’ve worked and worked with him and get seem to get it fixed fully{his velocity is down sometimes also}.Is there any suggestions?

Could be a number of things. Do you have any video of him that you can post so we can look at his mechanics?