Matt Cassel, a career backup in college and in the pros, parlayed a great 2008 season into a lucrative franchise tag. Now, he's locked himself into a deal to be the long-term quarterback of the Kansas City Chiefs.

Cassel and the Chiefs worked out a six-year deal that will pay him in excess of $10 million a season, according to a source. The contract will keep Cassel with the Chiefs until 2014.

The deal is for $63 million, with $28 million guaranteed, according to a source. He's going to make $40.5 million in the first three years of his contract.

Cassel was designated as the New England Patriots' franchise player in February and signed a one-year deal that paid him $14.561 million. He was then traded to the Chiefs along with linebacker Mike Vrabel for a second-round draft choice.

"We are excited to be able to reach a long-term agreement for Matt Cassel to be a Kansas City Chief for many years to come," owner and board chairman Clark Hunt said in a statement. "His proven leadership on and off the field will be a tremendous asset to the organization."