Matt Cain has been brilliant so far this Postseason. He's held batters to a .173/.259/.187 line over 21.1 innings. He's allowed 13 total hits, only one for extra bases, and has struck out 13.
When he broke into the league, Matt Cain showcased a mid-nineties fastball. He's turned into more of a finesse pitcher, with his fastball now averaging around 92 mph. As a result, Cain no longer blows away batters with high cheese as much as he once did, but instead relies on his secondary pitches more.
During the regular season, Cain tended to get hit harder up in the zone. Against lefties, pitches down and in were hit hard as well.
Cain has been extremely efficient at avoiding throwing to those danger areas in the postseason.
As the heatmaps indicate, Cain has avoided throwing in to lefties, an area that has given him trouble. Overall, he's also avoided sailing fastballs up in the zone to both hitters. This kind of control is a big part of his great success so far in October.