QB value fades quickly in the draft.
In a class with candidates like Scam, RGIII, Luck, Mariota, Winston - they tend to go off the board immediately, followed by a break until Rd 3 when another tier will be drafted in the middle of Rd 3 to the end of Rd 5 with no real dynamism to "get their guy" evident.
Unless a QB prospect is among the kind of prospects that are viewed as "can't fail", they actually don't have much of a market value at all.
2nd tier QB prospects are worth no more than any other positional prospect expected to need time to develop, even though the position itself is valued quite highly.
In that sense clubs are hesitant to waste a pick in the middle rounds on a QB, when other position groups, (like WR in 2014 & 2015), are deep indeed and can provide quality mid-round picks like Martavis Bryant, John Brown, & Donte Moncrief.
It's not until Rd 5 or later, when other position groups have been exhausted, that GMs are willing to take the chance of wasting a precious draft pick, (they only get 7), on a player that has extremely high odds against him ever playing a meaningful snap in the NFL.
Late round WRs, CBs, S, & LBs, are seen as better uses of picks than excess baggage QB prospects - because at least those groups can play valuable ST snaps.
QBs just sit around and play with their pencildiks and clip-boreds.
Petty went as high as a 4th round pick for only one reason.
The Jets were extremely desperate, or he'd have fallen another round and a half with Hundley, (who was deemed of roughly equal value).
