ESPN NFL Adam Schefter is reporting through sources that the Philadelphia Eagles have agreed in principle to a trade that would send All-Pro running back LeSean McCoy to the Buffalo Bills in exchange for linebacker Kiko Alonso.

The trade will not become official until Tuesday at 3 p.m. when the league year officially begins.

McCoy has spent his entire 6 year career with Philly, earning an NFL rushing title in 2013, two first-team AP All-Pro honors, 3 trips to the Pro Bowl, and led the NFL in touchdowns in 2011 with 20.

Alonso has only played one full season (2013), and missed all of the 2014 season with a torn ACL.

Photo by Rick Stewart/Getty Images

In his rookie year (2013), he played every defensive snap for the Bills, finishing the season with 159 tackles, good for third best in the NFL.

Alonso will be reunited with his college coach at Oregon, Chip Kelly, who enters his third season with the Eagles in 2015.

A trade like this is extremely rare in the NFL, seeing a superstar at a skill position traded anywhere is seldom. The fact that McCoy is being traded for a player coming off a torn ACL only makes it more unique.