I guess that would make sense, considering it could be A) a small sample size B) if you set your guard to -1, his 3pt FG% would be higher considering he's "mostly" taking wide open threes and not forcing any shots from the perimeter. There are definitely a lot of variables that need to be taken into consideration.
Supposedly, PE, Speed and then BH play an important part, possibly in that order, but think athleticism and low post rating may play, at least, a small part as well