Kafziel, from my understanding Tommy wasn't really deaf, dumb, and blind - he could see but didn't really understand what he was seeing, and he could hear - it just didn't make much if any sense to him. By dumb, I believe he meant mute. I could be wrong, but how would Tommy be staring in mirrors if he were really blind? He's simply blind to reality, and all he seems to see is his reflection.
Also, as far as I know, the actual pinball part to Tommy really isn't important to the true meaning and plot.
Kafziel, from my understanding Tommy wasn't really deaf, dumb, and blind - he could see but didn't really understand what he was seeing, and he could hear - it just didn't make much if any sense to him. By dumb, I believe he meant mute. I could be wrong, but how would Tommy be staring in mirrors if he were really blind? He's simply blind to reality, and all he seems to see is his reflection.
Also, as far as I know, the actual pinball part to Tommy really isn't important to the true meaning and plot.