He made his first season start on July 4 against the Texas Rangers. He went 0 for 2, ground and flying out in a 2–4 loss. On July 21, Molina was traded to the New York Yankees, making Napoli and Mathis hold the two catcher positions for the rest of the season. The trade also indicated the Angels’ confidence in Mathis. Overall in 2007, Mathis played in 59 games, accumulating 36 hits, with 12 doubles and 4 home runs while accruing a .211 batting average. On July 23, 2008, Mathis had 4 hits and 6 RBI (the highest in a single game for both categories that season) in a 11–14 win against the Cleveland Indians. Mathis noted that his team's pitcher, John Lackey, "obviously didn't have his best stuff today, but he kept battling through it... and luckily we were able to put some runs on the board for him." Overall in 2008, Mathis played in 94 games, the most in a single season. However, he had a batting average of .194, below the Mendoza Line. In game 3 of the 2009 American League Championship Series, Mathis hit an 11th-inning walk-off RBI double, defeating the New York Yankees 5–4. In spite of his poor regular season stats (.211 batting average), he used his strong playoff offensive performance and excellent defensive skill to bolster his case for a raise to $1.3 million, beating the Angels management in arbitration. The arbitration hearing was also something of a watershed in the amount of consideration paid to Mathis' defensive statistics. The LA Times highlighted the stark comparisons with competing catcher Mike Napoli: "in 657 innings with the agile Mathis behind the plate, Angels pitchers had a 3.99 earned-run average; they had a 4.86 ERA in 758 innings with Napoli catching. Mathis also caught 17 of 69 attempted base-stealers for a 24.6% success rate; Napoli, who will make $3.6 million in 2010 but is coming off two 20-homer seasons, caught 13 of 87 attempted base-stealers for a 14.9% success rate". Mathis had been among the AL leaders in pitchers' earned run averages while behind the plate. In 2010, Mathis was ranked by Beyond the Box Score as one of the worst defensive catchers in baseball. He also matched his career-worst batting average of .194, while posting a sub-.500 OPS in over 200 at bats. Toronto Blue Jays On December 3, 2011, following the acquisition of