Isner has a great serve– he leans into his toss and then he springs up and out

when you add your knee bend on the serve your line of arc should be straight

front foot is up to pre load the weight transfer– back foot is set so the heal goes to the opposite net post to pre set the hip and shoulder rotation

Dusty Baker tip– pull your hand in — not nuts about the head angle– but it beats getting hit

to be able to rotate you must get the front hip to open by having the front foot more toward the net–bonus– knee and racquet below flight path–Yeich of the Brewers is doing this and he has increased his power