Son is on a program in college that incorporates a lot of Baseball Ranch and some Driveline training methodologies. I can say I'm a big believer.
He worked with a local trainer in HS that trains lots of pro pitchers in the off season. He was in great shape but not a ton of velocity gain IMO
In two months on campus this fall he jumped 4-5 mph. Says his arm has never felt better. If you read some of their stuff some of this is mental too. Arm feels great allowing you to mentally throw with as much intent as possible.