No convincing arguments on why not to hire him. Purely superficial reasons without any information on his skills philosophy and reputation in the league.
Mike McCoy's career:
2000 - Offensive assistant for the Carolina Panthers
2001 - WR coach for the Carolina Panthers
2002-2003 - Demoted from WRs coach and made an offensive assistant again for the Carolina Panthers
2004-2005 - QB/Offensive Assistant coach for the Carolina Panthers
2006 - QB coach for the Carolina Panthers (Jake Delhomme was the QB he threw for 2805 yards, 6.5 yards per attempt, 17 TDs, 11 INTs, sacked 22 times, 82.6 QB rating...incidently Matt Moore had an 87.1 QB rating this year with Karl Dorrell as his QB coach and Dorrell has never been a QB coach before in his entire career)
2007-2008 - Passing game coordinator/QB coach for the Carolina Panthers (in 2006 the Panthers were 15th in passing at 204.0 ypg, in 2007 with McCoy in charge of the passing game they dropped to 29th with 170.9 ypg, in 2008 they were 19th at 197.4 ypg...still not where they were before he took over)
2009 - OC/QB coach of the Denver Broncos (Denver ranked 15th in total offense and scored 20.4 ppg...however, I think Josh McDaniels actually called the plays that year)
2010-present - OC of the Denver Broncos (Denver was 13th in total offense that year and scored 21.5 ppg...again I think McDaniels called the plays up until he was fired after the 12th game. In the last 4 games Denver's offense put up 322.75 ypg and 20.25 ppg. They had been averaging 357.6 ypg and 21.9 ppg before he took over)
So tell me where the convincing argument is in favor of him...other than "I like what he did in Denver".