Out of all the new faces and cornerstones of the Philadelphia Eagles’ roster, undoubtedly the most important of those is quarterback Sam Bradford.

In what was arguably the most tumultuous offseason in Eagles history, Bradford was really the most important move Chip Kelly made. The entire city is counting on his ability to live up to his lofty expectations, and so far the consensus seems to be that he will do exactly that in Kelly’s offense. Clearly his anticipated high level of play will stabilize the roster for years, but there’s another half of that equation no one wants to talk about: What if he doesn’t?

What if Bradford goes out there and falls flat on his face? What if his knee gets hurt again and disintegrates into a giant pile of dusty failure? The short answer is that the Eagles would generally be screwed. Mark Sanchez, in all of his bumbling and butt-fumbling glory, won’t ever take this team to postseason glory. Not unless he stops being himself and starts playing like he’s someone else, anyway.

The longer answer is this: If you thought this offseason was nuts, you haven’t seen anything yet.

If Bradford doesn’t rise to the occasion and conclusively proves he’s a dud, Kelly will only have one move to make. Kelly is going to be bold like we never could have imagined, and he’s getting his franchise quarterback come hell or high water. You might as well forget the draft — fortifying the defense or the offensive line will have to wait. Kelly will sell anything that isn’t directly nailed to the floor in order to get whoever he targets as his quarterback.

Kelly thinks he’s on to something with Bradford, and he’s right. He absolutely is. But if it doesn’t work out, don’t think Kelly is going to wait until his fifth year with the team to find a starter. As much as he might like Sanchez, Kelly won’t be prepared to roll with him as his guy week in and week out. If he was, he would have done it already.

No, Kelly will mortgage the present, the future and the future’s future to land a passer he deems worthy of running his offense. Who knows, maybe it’ll be Marcus Mariota after all. Or maybe it’ll be a prospect like Connor Cook or Christian Hackenberg. Whoever it is, it’ll come at a ridiculously high price the Eagles will be paying for a long time. Unfortunately, franchise-quality quarterbacks don’t grow on trees and are rarely on the open market.

So keep your fingers crossed that Bradford takes advantage of the great situation he’s in. I truly think he can do it — I really put a lot of his struggles on bad luck and the coaching instability he dealt with in St. Louis. I think a change of scenery and a generous offense is exactly what he needed.

But if he’s just that bad of a player, buckle up your seatbelts and grab onto something solid. With a glaring need to fill and a blank check to do it with, Kelly could make this offseason’s shake-up feel like a gentle rumble.

Doug Green is a Featured Writer for www.RantSports.com covering the Philadelphia Eagles and the NFL. Follow him on Twitter @DGreenNFL.