3. Chet Holmgren
Oklahoma City has its own rookie sensation in the building (yes, he's a rookie; this is his first year suiting up). Chet Holmgren has taken the world by storm and is the current betting favorite for Rookie of the Year over Wemby, who we thought would win the award running away coming into the year. The ROY business is debatable, but Holmgren's impact on OKC's defense is not.
The Thunder were the 15th-ranked defense a season ago. Not good, not great. But it was a step in the right direction, factoring in the youth OKC has and had on its roster. They couldn't stop anyone from getting to the rim. Teams attempted 34% of their shots at the rim against OKC, a displeasing number that ranked 19th.
With Holmgren on board, their rim protection puzzle has been solved. OKC is the seventh-best defense in the league, and only 31% of their opponent's shots are coming at the rim. Of course, scorers will think twice about scoring over this wiry, twitchy, barely-legal NBA rookie. Sure, he has a slight frame and is young without experience, but the team-wide improvement and Holmgren's steadiness are his best DPOY case.