If I'm reading the two charts correctly, and if the two photos are representative, then the higher release point was giving Liriano a tighter snap and a better look-down angle, a phenomenon I recognize from tennis. A lot of people think that a good flat serve requires leaning as far as possible into the shot, thus theoretically giving you more forward thrust via body lean. Instead, the best serves are met higher in the air, with relatively modest body lean. The idea is to drive the heel of your hitting hand upwards and forwards, like a shot putter, then relax the hand at apex and let the racket head snap over naturally, like a mouse trap. If you do it right, you create an effortless wave of power that starts from your feet and moves up your body, ending in a loud bang as the ball explodes off your racket. A pitcher like Tim Lincecum does the same thing by executing what amounts to a low aerial cartwheel, using his entire body to create the power wave. That's why he's able to generate the fantastic power - he's using his gymnastic training to throw a baseball.
Liriano isn't going to throw himself through the air like Lincecum, but he is able to generate a lot of pop at the top if he gets upward thrust. That's why the higher release point works so well for him.