Leaderboard of the week: Red-hot Matt Cain

Philip Humber's perfect game was the most impressive performance of the week. But it actually finished tied for the best pitching performance of the season by one of our favorite metrics. And the pitcher whom he tied is worthy of attention, too.

Game Score, devised by Bill James, rates a pitcher’s start based on innings, runs, hits, strikeouts and walks. An average Game Score is typically 49 to 50. Almost every Game Score finishes between 0 and 100 and you can think of the rating as similar to a test score (the higher the better).

Humber finished with a 96 (in order to score a 100, he’d have needed four more strikeouts) for his Saturday game against the Mariners. He was the second pitcher to post a 96 this season. Matt Cain posted a 96 against the Pirates on April 13 when he pitched an 11-strikeout, no-walk one-hitter.

Cain’s last two starts account for two of the five-highest Game Scores this season. He registered an 85 or better in each of his last two starts.

It’s rare for a pitcher to post three straight starts with a Game Score of 85 or higher. Four pitchers did it from 1994 to 1998 -- David Cone (1994), Randy Johnson (1994 and 1997), Curt Schilling (1998) and Roger Clemens (1998). No one has done so since.

Cain starts tonight against the Reds, a team he was 2-0 against last season, allowing two runs in 17 innings.

What has Cain done best this season? How about this: Left-handed hitters are 4-for-43 against Cain in his three starts. Cain has succeeded by pitching left-handed hitters away. He’s thrown 72 percent of his pitches to lefties on the outer-third of the plate or further away. Cain started working lefties away with greater emphasis last season, when he threw 58 percent of his pitches to that area (up from 50 percent in 2011). It worked. He held lefties to a .185 batting average.