Scoot's RPM (Real Plus-Minus) is 402 out of 403 players in the ESPN database. There is literally one player in the entire NBA that he ranks ahead of in a rating designed to measure overall performance. The one player he ranks ahead of plays only 7.5 minutes per game, with only 15 games played, so likely the only reason Scoot is not literally dead last is Lindy Water's small sample size. Scoot has a -0.25 RPM Wins, compared to -0.06 for Lindy Waters (Hint: the lower the number, the worse). So yes, based on a widely used rating system designed to give a general idea of player performance, you can make a case that Scoot is the very worst player in the NBA.
Or, you can just forget the stats and watch the games. Anyone that understand basketball, and isn't a complete moron, can see how unbelievably terrible he is. The statistical analysis just verifies what should already be obvious.