"It's shocking that a guy who's been such an important part of their organization, that they'd want to get rid of him," Manning told Reuters after an appearance in New York. "He's had great seasons these last couple of years."
The Eagles actually finished ahead of the Giants in the division last season, but Manning's status isn't in question. He's won a championship.
But the 33-year-old McNabb, who completed 60 percent of his passes last season with 22 touchdowns and 10 interceptions, hasn't been able to get Philadelphia over the hump. The closest he got was a Super Bowl loss to the Patriots in 2005.
And with youngster Kevin Kolb and veteran Michael Vick on the roster, McNabb might be the most marketable. Sources have told ESPN NFL Insider Adam Schefter that the Raiders, among other teams, are interested.
"You kind of heard rumors the last couple of years," Manning said, according to Reuters. "I'm kind of waiting to see if something truly happens.
"Donovan has been a tremendous player for the Eagles, a staple of their organization. He's a tremendous competitor and a tremendous person."