Kansas City, Mo. ? Matt Cassel’s rocky career in Kansas City came to an abrupt ending on Thursday, when the Chiefs released their former starting quarterback with two years left on his contract.

The decision to cut ties with Cassel came one day after new general manager John Dorsey and coach Andy Reid held a news conference to introduce Alex Smith, whom they landed in a trade with the San Francisco 49ers to be their quarterback of the future.

Cassel was the first major acquisition by the Chiefs under previous general manager Scott Pioli, and he was quickly given a six-year, $63 million contract. But after leading the Chiefs to the playoffs in 2010, Cassel struggled to live up to the same expectations.

He sustained a season-ending hand injury two years ago, and then lost his job to Brady Quinn after sustaining a concussion last season, spending the rest of the year as the backup.

The Chiefs had been trying to trade Cassel for a late-round draft pick but, having found no suitors, decided to release him and carve out additional space under the salary cap. He would have made a base salary of $7.5 million this season.

Hours later, Cassel reached an agreement to join the Minnesota Vikings as the backup for Christian Ponder, according to person with knowledge of the deal who spoke on condition of anonymity because the deal had not been announced.

“He’s a good football player and deserves the respect we’re going to try to give him right now,” Reid said. “We think that’s important.”

Cassel started 47 of the 48 games he played for the Chiefs, throwing for 9,549 yards with 59 touchdowns and 44 interceptions. His best season came three years ago, when he threw for 3,116 yards and 27 touchdowns with only seven interceptions, and led the Chiefs to the playoffs.

He seemed to be validating the deal made by Pioli to acquire him from New England.

Then everything began to unravel.

He went 4-5 as a starter in 2011 before hurting his throwing hand late in the season and landing on injured reserve. During the offseason, when he appeared in a celebrity softball game as part of All-Star Game festivities at Kauffman Stadium, he was booed lustily by the crowd.

The Chiefs fired coach Todd Haley and appointed Romeo Crennel his successor, and Crennel stuck with Cassel last season.

But he went just 1-7 in eight games under center, and some fans at Arrowhead Stadium cheered when he sustained a head injury in a loss to Baltimore.