Can Masterson shut down Boston's lefties?

As expected, the team with the best record in baseball begins a three-game series at Progressive Field tonight (7 ET on ESPN2 & ESPN3.com). But it’s the Cleveland Indians who sit atop the majors, not the visiting Boston Red Sox.

Justin Masterson

MastersonJustin Masterson is a big reason that the Indians have allowed the fewest runs in the American League. He won his first five starts and currently sports a 2.52 ERA.

Since Cleveland acquired him from Boston as part of the Victor Martinez deal in 2009, Masterson has also pitched well against the Red Sox.

He did not face his former team when Cleveland swept Boston in the season’s opening week. But in two starts against the Red Sox last year, he surrendered one run in 14 innings and held them to a .133 average, as the Indians won both games.

The right-handed Masterson has limited right-handed batters to a .141 batting average, the lowest of any major-league pitcher this year. Lefties are hitting .326 against him, the fourth-highest average in the majors (minimum 100 PA).

Left-handers have an OPS against Masterson that is over twice as high as right-handers, and righties both miss and chase his pitches at a much higher rate.

Justin Masterson This Season

Those differences could prove dangerous for Masterson tonight. Seven of Boston’s nine regular hitters bat left-handed, including switch-hitters Jed Lowrie and Jarrod Saltalamacchia.

Curiously though, of those seven batters, six have faced Masterson before (Gonzalez excluded), and they have combined for a .185 average (5-27) with 2 home runs.

Another key for Masterson will be continuing his success at inducing ground balls. At 59.7 percent, he has the fifth-highest ground-ball rate of any pitcher this season. According to Fangraphs, the Red Sox are an average team in that category this year, ranking eighth in the American League at 44.3 percent.

Justin Masterson and the Indians go for their sixth straight home win over the Red Sox, tonight at 7 ET on ESPN2 & ESPN3.com.