Maybe, just maybe, he wasn't as good a guitarist at that time that he is now. And yeah, maybe he could write the solos but a good solo in the hands of a bad guitarist (I'm not saying V was ever bad, don't go there) does, in fact, make a bad solo. Or maybe he just had a friend who was slightly better than him and liked him to lay down the solos to get the best result out of the assets he had in his vicinity.
These are just guesses on my part though. I don't have the slightest clue.