The departure of NHL writer Mike Chambers shortly before the world champion Colorado Avalanche started the regular season wasn’t the only recent high-profile exit from the sports staff of the Denver Post. Broncos beat writer Ryan O’Halloran left the paper after the second week of what has been a very disappointing season to begin covering one of the best teams in the National Football League, the Buffalo Bills, as well as the pro-hockey franchise Buffalo Sabres, for the Buffalo News…