Pitching Out of Stretch

I wouldn't because then it makes it tougher to disengage with a jump turn pick off.  If you're balanced then you're better position to go home or go with a pick off.  Plus, what benefit is there to loading all your weight on back leg?

I always would like to put 75% of my weight on my back leg. I think it gives you more momentum as you drive forward thus creating an increase in velocity.

I am assuming you are a RHP asking this assuming you are holding a runner on, correct?  Assuming this is the case, it depends on how fast your move is doing his.  For a RHP, the amount of weight shift (load) depends on several factors, specifically on whether you can hold most of your velocity with an abbreviated leg lift, as well as your ability to command your pitches.  I have seen far too many cases where a young pitcher alters his mechanics far too much with runners on base, and then can't find the strike zone, or he finds he can't spot pitches, and gets hit hard.  Controlling the running game is important, however it cannot be at the expense of "pitching" and resulting in "throwing".  Done correctly, you should be able to load your hips with an quicker abbreviated leg lift out of the stretch without losing too much velocity.  The key is not to lose the ability to fire the hips, and instead just rush to foot strike....they are not exclusive of each other.

Coach,
I had a pitching coach tell me  that by putting all your weight on your back leg that when you go into your leg lift it helps you lead with your hips and creates more momentum going down the mound.  The only issue is the pickoff move.  Just wondering what the rest of you thought

I am with BFS on this one. If it is indeed a RHP, then with a runner on second you can still load and rotate, so if the pitcher is concerned about holding a runner on first then the best defense for this is to... hold..hold..hold..hold. Messing with mechanics just makes the situation worse IMO. 

 

I would also point out that many young pitchers don't "load and go" properly and get weight back behind their post leg instead of lifting and driving. 

 

Young baller, your coach is correct. You can also load and jump turn. One other thing that young pitchers don't do is practice their pickoff's a lot practice this during non throwing days.