Many driveline guys work in pro ball in hitting now.
Ochart has worked for the Phillies the last couple years.
Colin hetz is a hitting coordinator with the Mets. I think the reds also have a driveline guy.
I think they are really good now. I think the first couple years they were more "take heavy bats and swing for the fences" but over the years they have really gotten a lot better and some of them now are also really good at improving mechanics, especially when it comes to being able to pull the ball for power. They really work hard to get better and try to also get to new areas like improving plate discipline and making more contact.
That being said I still think they are best at taking underpowered hitters who can make contact and improve their power by optimizing bat speed and bat path.
Teaching guys who whiff a lot to hit they are not as good yet, but then again nobody is and they are working hard on it and if somebody finds it out it might be them.