Wemby has been ascending pretty rapidly, and Chet has hit a plateau of sorts.
Over the last 15 games, Wemby has put up 25 a game on 53 percent shooting, 9 rebounds, and 3.5 blocks all in 25 minutes of play a game.
Chet has put 16 a game on 55 percent, 6 rebounds, and 2.3 blocks, in 31 minutes of play a game in that same time frame.
Wemby is also a better defensive player, although for sure Chet is very good himself.
IMO, there is a tier-difference between them as players.