What's worse than losing your star running back? Losing him to one of your biggest rivals.

ESPN is reporting that Dallas Cowboys running back DeMarco Murray has signed a five-year, $42 million contract to join the Philadelphia Eagles. $21 million of the contract is guaranteed.

ESPN reported earlier that Murray called Eagles coach Chip Kelly personally on Wednesday to express his desire to play in Kelly's high-powered spread offense. The Eagles traded for quarterback Sam Bradford, who was Murray's teammate at Oklahoma, earlier this week.

"It was never about the money in any situation," Murray told ESPN.com's Todd Archer. "If it was the money, I could've taken that a long time ago on a very high deal. It's about winning a Super Bowl and being fair."

Murray was the 2014 NFL rushing leader with 1,845 yards and 13 touchdowns. Last season was the first for Murray to play all 16 games. He missed 11 games over his first three seasons because of various injuries.

Do you think the Cowboys made a mistake letting Murray sign with Philly? Let us know your thoughts in the comments below.