At high skills, it is hard to classify a player as PF -- he would need a lot of JS, compared to his inside skills. Given the small influence of his outside skills, many people just field a C with some secondaries there, which would be one of their more skilled Cs (in terms of JS and OD), but won't be listed as PF.
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."