His stamina is average. so shouldn't really be a factor.
Last season he shot 73%, the season before, 84%, before then, 76%.
So shooting below 70% is just crapola for sensational FT.
Sure if he has a good game, goes to the line 10 times, and makes 8, he will be at 71%, but its just still a bit annoying overall. Some of the other guys shoot lower than what i would be expecting.
I remember i had a guy who had Wonderous FT, and he just shot the lights out, like 90% plus for the time i had him.