Yea, I played semi-pro up until I was 30. I wasn't a pitcher though.
I was also in the fitness industry during that timespan, and had a good amount of experience with sport specific training.
Perfect example of what can happen: My final year playing I was training in the gym doing rope hammer curls on the cable and felt a "pop" in my right forearm. Minimal pain until I hit the field. Started throwing and out of nowhere had very little control where I was throwing and felt a dull pain in the inner elbow/forearm that started intensifying the more I attempted. The pain eventually got to the point it made me nauseous and I don't get that way easy.
Went to the doc and sure enough, I blew a ligament right at the elbow/inner forearm area that would have required surgery, had I chose to continue playing. So thats when I hung it up.
And thats a perfect example of why you have to be extra cautious in your situation.
By taking PH's you are creating the environment to demand your body to do things it normally could not tolerate, and that's when injuries occur, let alone all of the other risks you would encounter without even playing a sport.
So you have to ask yourself, are those risks worth the extra 1-2 MPH on your fastball? Will you even gain 1-2 MPH on your fastball?
Fact is, you could LOSE some ROM in your throwing arm from a safe and effective PH run and lose velocity. Who knows.
If I were you, I'd be focusing more on fine tuning your offspeeds or perfecting a "different look" via arm angle or delivery method if you are not doing so already.
Also, keep in mind. You are a baseball player. Baseball players don't have to be athletes to make the HOF. Not all athletes have the gift to be able to hit a ball at 90 mph or have the knowledge or precision a pitcher has to strike someone out.
You are a different breed of "sport".
So just be careful OP