Often times, offensive flow seems completely insignificant. There are teams in my league who throw down awful/inept offensive flow without missing a beat and I've seen teams with Respectable offensive flow who don't seem to benefit from it much.
I spent most of last season training my PG's, naturally training passing sometimes. I notice, however, that many other teams play SG's at the PG position and are very successful.
Despite these indications that having a PG with really great passing is not important, PG's typically go for very high values on the transfer list. What's up with that? PG is also a very easy position to train, which should dampen PG prices, but that doesn't seem to be the case.