If the Browns sign McCarron as their starter QB they will be able to hold the rest of the league hostage to their demands for either #1 or #4 . . . or both.
Fans need to see how FA plays out before going all in on the draft itself. All it will take to blow the QB hunt out of the water will be for McCarron, Cousins, Keenum, Bradford, Bridgewater, etc to sign on as starters (or even bridge QBs) and the entire dynamics of draft order and teams who need a QB shifts dramatically.
The biggest feeding frenzy will occur if the Browns sign a QB and put their picks on the market. Teams will see that shiny top pick at #1 and even #4 as too precious to pass up---even when its not. Browns could sign McCarron, take RB Barkley (top player in this draft) and put that #4 up for bid---they trade down in this year's first and hoard more picks for next year. They get a QB, a RB, and a top player at his position + picks/other players. That is why the Browns might trade down. Even if McCarron falls flat, they can get to the head of the line for QB next year.
All the trade up talk surrounding the Cards at #15 is way premature. Too many QB moves on the horizon with FA that will flush all these fan speculations down the river.