Lack of command is almost always the result of poor throwing mechanics. And it’s usually more than just one thing. It usually begins with one specific bad move that creates a chain of other bad moves. None of the bad moves ever repeat themselves the same way in sequence so the throwing motion isn’t repeatable. I agree that it’s probably time to find a new pitching coach. Unfortunately there aren’t very many that are competent in teaching the complete throwing motion. I like to compare the complete throwing motion to a pie that has been cut into 8 pieces. It’s not hard to find a pitching coach that can teach about one or two pieces of the pie. But it’s very hard to find someone that can teach about the whole pie. Corpus is a baseball hotbed so maybe there is someone good down there. I know one of the Asst Coaches at Texas A&M-Corpus Christi and I will ask him if he has a name that I can pass on to you. If he does I will send it to you in a PM. Good luck!