Week 4 against the Pittsburgh Steelers, due to a rib injury to starting quarterback Christian Ponder. The Vikings won the game 34–27. Due to another injury to Ponder, Cassel received his third start of the season Week 14 against the Baltimore Ravens. Despite a two-touchdown, zero interception performance, the Vikings lost by a score of 29-26 during a heavy snow game. He would remain the starting quarterback the rest of the season where the Vikings finished with a 5-10-1 record and Cassel either played the whole game or came in to rally the Vikings from behind in all five victories. On March 7, 2014, it was reported that Cassel had signed a new two-year deal for $10 million. It was later announced on August 25, 2014, that Cassel would be the starting quarterback over rookie Teddy Bridgewater and Ponder. However, on September 21, 2014, Cassel broke his foot against the New Orleans Saints and was placed on injured reserve. In only three games, he totaled 425 passing yards, three touchdowns, and four interceptions. Buffalo Bills On March 10, 2015, the Vikings traded Cassel along with a sixth round 2015 NFL Draft pick to the Buffalo Bills in exchange for a 2015 fifth round pick and a seventh round pick in 2016. Cassel was involved in a three-way quarterback competition between former Bills first round pick EJ Manuel and former Ravens backup Tyrod Taylor. After losing the competition to Taylor, Cassel was released by the Bills on September 5, 2015. However, he was re-signed three days later to back up Taylor. Cassel was credited as the Bills' starting quarterback for the season opener due to him taking the team's first snap on offense in the wildcat formation with Taylor lined up at wide receiver. Dallas Cowboys On September 22, 2015, the Bills traded Cassel to the Dallas Cowboys after Tony Romo suffered a broken collarbone. In addition to Cassel, the Cowboys also received Buffalo's 2017 seventh round pick (#228-Joey Ivie) in exchange for Dallas' 2017 fifth round pick (#171-Nathan Peterman). Although Brandon Weeden was expected to start, the Cowboys covered themselves by also trading for Cassel. After Weeden lost the three games he started, Cassel replaced him as the starting quarterback while the injured Romo continued to rehab. He was never able to have any sustained offensive success and was prone to critical errors. On December 19, after a disastrous showing