I rarely fish for bass, but when I do all the flies are at least 4 inches long.
I still catch a good number of larger bass with smaller flies. I use size 10 & 12 alot for bluegill. If I get it right in front of a large bass they will not reject it.
I think presentaion has alot to do with getting the bass to hit smaller flies.
If you don't make them move far ( expend energy) they will hit the fly.

Rick