Perhaps the most important questions regarding the future of the Dallas Mavericks: can Kristaps Porzingis return to being an elite defensive player? That will depend on if Porzingis has lost the physical ability to be a good defender.
Porzingis is a massive human being. He also is, or was, a gifted athlete for someone of his size. Players of similar height or length generally have athletic shortcomings. The only people listed at least 7-foot-3 in NBA history who come close to matching Porzingis athletically are Ralph Sampson and potentially a Pre-NBA Arvydas Sabonis.
Historically, Porzingis was able to leverage this incredible height and length to great effect as a rim protector.