i found this video to be pretty useful and for once on youtube someone who actually knows what there talking about.
“Front leg momentum”–I like this line. Too many pitchers are not aggressive enough with the front leg after peak knee lift.
I disagree with the front leg extending. Yes it (the muscles) should firm up the leg to the point of stopping the momentum toward the plate, but not to the point of straightening the leg. The straightening of the front leg is just a “reaction” or an “over-exertion” of the muscles. The front leg should be working to decellerate the momentum toward the plate, not accelerate the front hip up or back toward 2B. It should be working in an eccentric and isometric manner, not a concentric manner.
Brandon Morrow throws high 90’s with a bent front leg. It only straightens well after release. Matt Cain is another hard thrower who has a “soft” front leg and rarely ever straightens his front leg, even when his control is way off. I’d say those who straighten the front leg are “cheating” or using it as a last resort to gain velocity.
But that video really seemed like it was well thought out.