Mayer shot 40/32/70.
Grandison 45/41/82
Next question
Sure: Why are you comparing a 6-6 3-guard with a 6-9 forward?
Anyway, if you look at field attempts per game, you're talking about a whopping 1.4 missed shots per game difference.
Mayer: 8.8*.6 + 4.12*.68 = exp. 8.1 missed shots per game
Grandison: 7.4*.55 + 4.4*.59 = exp. 6.7 missed shots per game
Mayer averaged 8.8 rebounds over 40 minutes. Grandison averaged 6.0. In real terms, the difference was 1.2 rpg, so Mayer essentially makes up for any field goal shooting discrepancy even if they played the same role and we ignore that Mayer's team was 1 seed who tied for a conference title with the national champs.