If you look at the NBA's clutch-time statistics (final five minutes of a game with a score differential of no more than five points), the aforementioned three players with the most offensive upside don't look too great as clutch-time players. That's because their defensive ratings during those moments are not too great.
Using NBA.com's offensive and defensive ratings, which project the number of points produced individually per 100 possessions, Kuzma is 16.4 points worse on defense than offense, Ball 10.5 worse on defense, and Ingram 8.7 worse on defense.
Furthering the problem is that the players supposed to be the glue bonding the defense with these guys have similarly failed: Larry Nance (25.9 points worse on defense than offense), Julius Randle (16.2 points worse), Josh Hart (15.3 points worse) and Kentavious Caldwell-Pope (9.2 points worse). These are all small sample sizes, but Clarkson's clutch defensive rating is particularly alarming at 180.4, basically the worst of any player to have played the clutch minutes he has.
Fantastic article by Kevin Ding of the OC register. Some very revealing data has been presented which should come as a bit of a surprise.