Williamson's tenure with Boston was a troubled one: his ERA with the team was 6.20 and he pitched just 20 innings in 24 appearances. In mid-September he underwent an MRI but the result was negative. As Boston entered the playoffs he shared closer duties with Mike Timlin. In the American League Championship series against New York, Williamson earned saves in Games 1, 4 and 6. Nevertheless, Little left a tiring Pedro Martínez in the 8th inning of Game 7 with Boston up 5-2. Martinez gave up three runs and New York would eventually win in the 11th inning 6-5. Critics maintain that Little should have pulled Martinez in favor of Williamson or Timlin, but that their mixed record during the regular season led Little to stay with the veteran Martinez.