One day, you’re reinventing your career as the prototypical Patriot, redefining your role as a sacking and intercepting linebacker and even crossing over to offense to catch touchdown passes as a tight end. The next day, you’re getting traded to the Kansas City Chiefs. Vrabel had perhaps the worst jettisoning of the Patriots’ fan favorites. His inclusion in the deal that sent backup quarterback Matt Cassel to the Chiefs surprised many. But Belichick was again proved right — Vrabel’s best years were behind him, although the sudden move was hard for a team that had come to depend on Vrabel as a leader and on-field producer.