03-04 ROY Lebron James FG% .417
05-06 ROY Chris Paul FG% .43
07-08 ROY Kevin Durant FG% .43
Beal is his only real competition for ROY shooting percentage is not as important as points/per which is largely about volume of shots with John Wall injured I think Beal is the favorite to win ROY but if Cleveland is plus 15 in wins and Dion averages 16+ a game he has a shot. Defensive players almost never win ROY.
I don't think Dion will average 16 a game. And I think Barnes is likely to average at least that. To me, the legit candidates are:
Anthony Davis
Harrison Barnes
Bradley Beal
Donatas Motiejunas/Jeremy Lamb (one of them is most likely going to step up, my bets are on Motiejunas)
Jonas Valanciunas
Damian Lillard
Michael Kidd-Gilchrist
and then Dion.
But looking at the past rookie of the year winners:
Chris Paul: 43% from the field, 16 points, 8 assists, 5 rebounds, 2 steals. Dion could possibly hit 16 and 2 (I personally don't think he will, but he could), but he won't come anywhere near 8 and 5.
Brandon Roy: 45.6%, 17 points, 4 assists, 4.4 rebounds (Pretty unlikely he'll hit those numbers)
Kevin Durant: 43%, 20 points, 4.4 rebounds (not likely)
Derrick Rose: 47.5%, 17 points, 6.3 assists, 4 rebounds (highly unlikely)
Tyreke Evans: 46%, 19.5 points, 5 rebounds, 5.6 assists (not going to happen)
Blake Griffin: Not gonna bother with the statistics since he's a big man, but the guy was an All-Star and was an absolute beast.
Kyrie Irving: 47%, 18.5 points, 5.4 assists, 3.7 rebounds (not gonna happen).
So yeah, I don't think it's very likely Waiters will win ROTY.