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.