Elite is hard to define. At any given time, there are roughly 450 NBA players. Is elite top 10% (top 45)? Top 5% (top 22)? Top 1% (top 5)? If your definition of "Elite" is top 1%, then no, Derrick White isn't elite at anything. Is he a top 20 defender in the league? Always tough to compare guards and bigs. But say there are 150 guards in the league, top 5% would be top 7 or 8.
He may be that, he may not. I mean is he a better defender than Smart, as an example? Obviously, Smart was hurt most of the year and only played in 20 games, so he clearly didn't have a better season, but entering next year if both are healthy (and the injuries don't diminish Smart), who are you calling the better defender? It may be White or it may be Smart. Did someone like Thybulle forget how to play defense or is him just being on a terrible Portland team the reason he doesn't get the love like he did when he played for Philly? And I wasn't joking when I said I didn't even know if White was the best guard defender on the team. Holiday is obviously fading, but he was an elite defender in his prime (and he was 1st team all defense even just last year). Jrue may still be a better defender than White, especially in crunch time (I do think White can go at it harder for more of the game, but at their peak, I'd probably still take Jrue - though that gap is closing). And in the actual defensive metrics of the rotation players, Tatum actually led the team in defensive win shares (White was 2nd just a smidge ahead of Brown) and Horford led the way in DBPM (white was the top guard but was behind Kornet and KP).
As I said, White isn't Caruso, Suggs, or SGA as a guard defender. Those guys I consider to be elite defenders and I just don't think White is in that class. Now maybe there is a tier below those guys that is still considered elite and White could very well be in that group, but I'm just not so sure of that. I do know White doesn't generate steals or blocks at an elite level. There is obviously a lot more to defense than creating turnovers, but they are easily measurable stats.