No...this trade is a bad idea.
First off, there's no guarantee that Biyombo will be available at 12. The trade as such is contingent upon the Raptors drafting a player they intend to trade - but only if another player they want is available 7 picks later? Stupid draft strategy. What if Biyombo goes to Detroit? Does that mean the Raps are stuck with Knight? If so, Knight would be the wrong player to take at 5.
Also, the crazy PF logjam is actually made worse with this trade, which doesn't address any of the Raptors real needs. Unless they try Millsap at the 3, but that's not a good idea. He's too slow there. And even if he did play the 4, I like Davis better. Millsap's defensivee numbers are equal to those on offense, which makes his contribution basically nil.
Or they get Jefferson, but for all the frustration fans have with Bargnani, why would we want another player who doesn't play defense? And the salaries don't match here at all. So unless there's another team or other players involved, it can't be Jefferson. So it's Millsap.
Just a bad trade.