Every player in the NBA had their Speed rating re-evaluated based on 2014-15 Player Tracking analytics which included player’s top sprint speed and timing. The Morris Twins maybe are so different because one plays PF & C & isn't running as fast up & down the court, as the other one who is playing SF/PF. As for the other guys, plenty of them don't give it their all & probably never fully sprint up & down the court. But I do believe it can use another look. A few centers seem way to slow, especially for the ones who are known to get out in transition.