Tim Tebow already has several challenges--his awkward throw, his slow delivery, others' over-the-top expectations--to overcome if he wants to achieve success as a quarterback in the NFL. Add to the list his sinister disposition: his left-handedness. ESPN reports that only 12 left-handed NFL quarterbacks have started more than 50 games in their careers. Some scouts and coaches think that a left-handed quarterback changes the entire offensive concept, and perhaps even the way the ball spins. "I know a lot of coaches who feel like they can't coach a left-handed quarterback," Scouts Inc.'s Gary Horton tells ESPN. "There are certain challenges that some coaches don't want to deal with." Others interviewed for the story say there's not much difference, and they point out that Broncos coach Josh McDaniels worked with left-handed backup Chris Simms last year. Broncos safety Brian Dawkins tells The Denver Post that he likes Tebow, especially his outspoken Christianity, which has rubbed some people the wrong way. "I didn't have to meet him to know I had stuff in common with him, my faith, what he believes in, outspoken about it, not ashamed about it, and that's how I am," Dawkins tells the Post. Dawkins also discusses on-the-field elements, including the revamped Denver defensive line, which should make the Broncos tougher against the run. Meanwhile, former University of Colorado standout and NFL journeyman Matt McChesney retired from the NFL yesterday after a freak golf-cart-related injury ruined his ankle, according to The Associated Press. McChesney had a good chance of making the Broncos as a backup offensive guard or center, but now finds himself out of the league.