The only left-handed starter the Boston Red Sox saw in the American League Championship Series was Dallas Keuchel. In the AL Division Series, the Sox clobbered veteran southpaws J.A. Happ and CC Sabathia.
An argument can be made that Boston hasn’t faced a left-handed starter equal to or better than Clayton Kershaw or Hyun-Jin Ryu in these playoffs. They’ll put that idea to the test quickly: Kershaw starts Game 1 and Ryu starts Game 2.