Aaron Rodgers seemed to loathe Mike McCarthy from the moment the Green Bay Packers hired him in 2006. McCarthy had been offensive coordinator of the San Francisco 49ers when they passed on Rodgers in favor of Alex Smith.
"Aaron's always had a chip on his shoulder with Mike," says Ryan Grant, the Packers' starting running back from 2007 to 2012. "The guy who ended up becoming your coach passed on you when he had a chance. Aaron was upset that Mike passed on him—that Mike actually verbally said that Alex Smith was a better quarterback."
Another longtime teammate agrees: "That was a large cancer in the locker room. It wasn't a secret."
Even during the best of times, Rodgers would regularly vent about McCarthy's playcalling and that he used the wrong personnel.
"Mike has a low football IQ, and that used to always bother Aaron," this source says. "He'd say Mike has one of the lowest IQs, if not the lowest IQ, of any coach he's ever had."
For a lengthy piece, Tyler Dunne spoke with dozens of players, coaches and personnel men from the Rodgers and McCarthy era, and many cite the relationship between those two as keeping the Packers from fulfilling their potential.