Bullpen session. Need advice

Hello all. I’m an 18 year old rhp senior almost two years out of tommy john surgery. Threw a bullpen today and felt pretty good. My arm is weaker than I would like but I can work on that. Right now I top out at 78-80mph and sit around 72 which is not good for the varsity talent in my district that I will be facing. I’m a small guy at 5’7ish 125lbs put have always had a pretty strong arm. The only problem I had while throwing my bullpen was when I would separate my arms and start to take my arm instead of going straight back parallel to my body I would go almost straight to the side perpendicular. Here’s a picture to help visualize lol. Is this a common thing and how big of a problem is it? Thanks for the help.

From what I can see, visualizing your motion, you appear to be throwing from a 3/4 arm slot instead of straight overhand, and there’s nothing wrong with that. If you’re comfortable throwing 3/4, stay with it. What you want to do is to be sure to get your whole body into the action—drive off the lower half of the body, using the legs, the hips and the torso in one continuous motion, which is ow you get the power behind your pitches, and your arm and shoulder will just go along for the ride so that you will throw harder and faster with less effort. Also, you might want to put on a little extra weight—you’re kind of skinny for your height! Maybe fifteen pounds will help.
And be sure to complete your pitches. When you follow through you want to throw more or less across your body so that you will end up in a good fielding position. You might want to get a catcher and have him set up behind the plate and position his mitt in various places, high, low, inside, outside, and you can throw to his glove, making sure to follow through. 8)