Why didn't Kyle Orton start?

It is simply amazing the difference Kyle Orton has made. Even the defense seems to have gotten a lift and we are now 7 yards away from a touchdown that will put the Broncos back in the game.

If Orton has been able to be effective, it raises the question as to why Josh McDaniels did not start him to begin with. Probably, Orton is still hurt and McDaniels was hoping Simms could be effective and give Orton just a few more days to recover. Simms wasn't effective, so Orton was forced into service.