Because here are the non-fictional Browns' past few first-round picks: Tim Couch, Courtney Brown, Kellen Winslow, Braylon Edwards, Brady Quinn, Trent Richardson and Brandon Weeden. Wow. Movie GM Kevin Costner is most likely going to do better, because this movie can pretend his pick's fictional career was resounding success.
From what I've gathered online, the plot goes that the owner of the Browns wants to trade up for the first pick to select Joe Allstarqb out of State University and says Kevin Costner will be fired if he doesn't. I assume Costner pulls off the the deal. Or he doesn't, but is happy he stood by his principles of not sacrificing picks for players.