When Jimmy Johnson got to Dallas he pretty much immediately picked up two QBs: Troy Aikman and Steve Walsh. He got Walsh in the supplemental draft. He honestly didn't know who was gonna be his QB, he was hedging his bets, and he picked Walsh because he was his QB at Miami.
I don't have a problem with us trading a pick for Foles, even something as high as a third. I don't see any QB prospects in the third being any better, and none that Reid would have a better familiarity with.
Oh yeah, and Jimmy flipped Walsh for 3 draft picks a year later so...it was all good.