Anderson and Dorsey didn't outplay Quinn in Cleveland.
http://www.pro-football-reference.com/teams/cle/2008.htm
http://www.pro-football-reference.com/teams/cle/2009.htm
Quinn and Anderson were about even in '08. Quinn outplayed Anderson in '09. Dorsey was on a different planet of bad QB play and shouldn't have ever been in the mix. But, he was. Why? Because coaches don't know what the fuck they are doing sometimes. You should be pretty familiar with this as you have vehemently disagreed with a variety of things the Rams have done over the years.
Now, notice I didn't say Quinn played well anywhere. He didn't. You're absolutely right that Quinn has been pretty bad up to this point. But is that Quinn's fault or the product of being in a shitty situation in Cleveland? I'd say Cleveland had a lot to do with it.
Quinn will not get a chance to compete for the starting job with Matt Cassel in KC. The Chiefs believe Cassel is good enough to win a championship with. They're retarded, but that's what they believe.
The idea that the best players will play is just coach speak. It's bullshit. Coaches and GM's have their favorites(sometimes not even with good reasons, like Cassel) and a pecking order is established. A QB competition is rarely instituted.
I'd love to see Quinn get a chance to compete with Cassel, but it won't happen, and that's out of Quinn's control. It seems like he's been getting a pretty raw deal so far in his career.