When I was 12 I started doing 50 pushups before bed each night for a couple of months before the season started, and i noticed a fairly significant gain in velocity. I am now 18 and throw about 80-82, but have noticed my velocity to have plateued over the past year. I remembered the effects of the pushups and i was wondering if i should start doing them again along with other lifting. How much and how often should i do them? and do you think that they could hurt me (i know bench press can be bad)? thanks

Push ups are not so bad as bench press is.

The push ups might have helped increase your velocity but once that area of your body is maxed out, you have to maintain it and work on other parts too. Balance

Why not try it. Its a great exercise that promotes healthy shoulder function. At the begining of the movement with your chest on the ground the rhomboids get a good squeeze. At the extension, or at the top of the movement, you get good serratus anterior activation that pulls the scapula to the ribcage. You need good seratus function to have a healthy shoulder. It also helps with shoulder mobility because you get a good full range of motion.