Though this is not a head-to-head comparison, Jimmer Fredette really started to blossom in his sophomore season. Dallin Hall got better in his sophomore season.
If Hall has two more years to develop as a junior and senior, he can certainly further develop his skills and potential - just as we have seen with players like Elijah Bryant, Yoeli Childs, Jake Toolson, Alex Barcello, and so on. Especially, if he has good developmental coaching. All of those guys who played at BYU got a chance at playing at the NBA level, and at the least are playing professionally and making money in the game. Whether NBA or professional in another setting, that is Hall's goal - which is what we would want him to shoot for, as he'll improve as a player in doing so.
I think all of the players mentioned above had critiques by fans on the board, as is normal and fair, but they kept playing and improved and got a decent chance at the professional level. I think the same is likely for Hall.