During an appearance Thursday on ESPN2's "First Take," McNabb was asked whether Shanahan is a good fit for the Baylor quarterback known as RG3.
"No," McNabb replied. "I say that because a lot of times ego gets too involved when it comes to being in Washington."
He played for Shanahan in Washington in 2010, when the Redskins went 6-10, the QB was benched twice, and there were testy exchanges involving McNabb's agent and the team.
"I was misused. Absolutely," McNabb said.
"Are you going to cater the offense around his talent and what he's able to do? Or are you going to bring the Houston offense?" McNabb asked, a reference to the younger Shanahan's work with the Texans.
"If this doesn't work this year - we don't see the splash, like a Cam Newton splash - this could be it," McNabb said.