Why was it Tim Tebow in Denver today, and not Brady Quinn?

Despite the opinion of Denver-area billboard purchasers, I believed it would be Brady Quinn who got the call when the Denver Broncos were eventually forced to bench Kyle Orton. It wasn't. It was Tim Tebow. You know by now how Tebow fared. Despite passing numbers that weren't overwhelming, he somehow got the Broncos back in the game against the Chargers. They had a chance to win it on the final play, but came up short. I wonder what happened to Brady Quinn, though. Not that I'm arguing for or against Tebow, or saying that Quinn would've done better. You couldn't ask John Elway himself to get the Broncos closer then Tebow got them today. This post isn't about the merits of either quarterback. I'm just wondering what happened to Quinn. There were the preseason reports that Tebow wasn't even the third best quarterback on the roster. The Broncos official website even refused to declare a winner in Quinn vs. Tebow for the backup spot. It's still like th...