Joakim Noah: inside scoring F?

Is this a bug? A center with F inside scoring?

It wouldn't be a bug so much as an oversight/error when assigning ratings. However, I'm not sure it's even that. While Noah has started to regain his form this season, he shot below 40% in the paint last season. I imagine his rating will come up in subsequent roster updates, if his play warrants it.

Does the game not allow "G" or "H" grading?

F is too high for "You're Jaokim this guy's a star?" No-O.