I agree he's playing some pretty good footy and while his kicking could get better (he's no orphan there) he looks as likely to be the successor to Boak as Butters is. Although Butters is a better player I think Drew can only play in the midfield.
There's nothing particularly flashy about him but he wins his own ball and puts on a lot of blocks around stoppages, opening up space for the more creative players to go to work. Every successful team has a Willem Drew or two.