Maybe he typed it on the plane:

“I’m grateful to Jeffrey Lurie for allowing me to coach his Philadelphia Eagles for the past three seasons. I deeply regret that we did not bring this great city and its fans the championship they deserve. I was blessed to work with a gifted and hard-working coaching staff every day, and they will succeed wherever they go.

Finally, my players mean the world to me. I will miss them very much and I will be rooting for them to achieve their dreams. Life is all about responding to challenges and seizing opportunities.”