No denying Fous is an excellent rebounder, so we'd likely lose something there. But Bosko is decent in his own right, has better size, and is probably disadvantaged by being an outside shooter so is likely not in position to get as many boards as Fous just due to playstyles. When you strip out offensive boards to account for this, Bosko was averaging 6 defensive boards a night per 40 minutes, Fous only a slightly better 7.2, so much closer.