I had an umpire friend of mine call me up during the Blues Jays/Royals game to tell me that Marco Estrada was committing an illegal pitch on every pitch he made whenever there were no men on base. I took a look and I think my friend is correct. Estrada starts out in the windup position then without taking his pivot foot off the rubber, he transitions into the set position. https://youtu.be/iy3iT3FOSwQ The rule, 5.07.8.01[a] and is quite clear: The Windup Position The pitcher shall stand facing the batter, his pivot foot in con- tact with the pitcher’s plate and the other foot free. From this position any natural movement associated with his delivery of the ball to the batter commits him to the pitch without interruption or alteration. He shall not raise either foot from the ground, except that in his actual delivery of the ball to the batter, he may take one step backward, and one step forward with his free foot. The Set Position Set Position shall be indicated by the pitcher when he stands facing the batter with his pivot foot in contact with, and his other foot in front of, the pitcher’s plate, holding the ball in both hands in front of his body and coming to a complete stop. Preparatory to coming to a set position, the pitcher shall have one hand on his side; from this position he shall go to his set position. Looks to me that Estrada is making an illegal pitch. I suppose it's just another rule that the umpires don't bother to enforce, like pitchers putting pine tar on the ball.