When your timing is off and you're pushing the ball instead of throwing the ball, there will be a decrease in velocity. If the timing is off or the arm slot is off, you won't see the same thing.
His (left) elbow is lower than it should be and he's not pitching like he's coming off a slope. At times, his arm was where it was supposed to be ... but his inconsistency with his arm slot is what leads him to throwing pitches that no major-league hitter would swing at.