One would think that I'd know the answer to this with a college RHP in the family but I will fess up and admit, I really don't.

For a pitcher, just exactly what is a "heavy ball" and what are its benefits?

A heavy ball is a FB with late movement that sinks and produces grounders.

Do colleges really value a heavy ball? As a situational pitcher that throws sidearm, my son induces alot of grounders. Is there a stat for that? He has a heavy ball. But what he's being told is that if he doesn't throw 85, he's not D1 material.

I myself prefer a heavy ball, these are the guys hitters hate because when the ball meets the bat it feels like u just hit a ball of lead!! Movement is the key, I have caught many FB's over the years and these guys scare me, it doesnt have to be a 90+ fb to be called heavy, its the late downward movement that usually ends up with a broken bat

I am not sure if they keep those stats in college (GO/FO ratios). They do in pro baseball.
College coaches want pitchers that get people out, period.
Interestingly enough, I know of a school that will not take pitchers that fly out often, due to a short park. They prefer to spend their scholarship dollars on strike out guys and HR hitters. Not sure if most coaches recruit to their parks weaknesses or not.
The only advantage may be that heavy FB pitchers usually throw less in a game and keep their pitch counts down and keep the defense on their toes.

BTW, I got the impression that the word "heavy" FB comes from how the ball feels when it is caught by the catcher.

thats why those guys scare me... it hurts!!

The late sink is the key. Some guys just have a natural late sinking fastball. Its called a heavy fb because it does feel like you have just hit a ball of lead. And catchers will tell you it feels like you just caught a ball of lead. Of course the more velo that this pitch is thrown with the heavier it becomes. These guys break a ton of wood and induce alot of gb's. Usually they have low pitch counts due to the fact they pitch to contact with little fear of getting hurt as long as they are down in the zone.

Son was told today by his coach that he had a really effective heavy fb. I just acted like I knew what he was talking about..lol.

Knowing now WHAT it is and it's effect I guess it's a good thing to have. My first initial thought was that son was throwing really, really slow! LOL