Opponent Pitching Stats

You know batting average, on-base-percentage (OBP), and slugging percentage (SLG). Three simple stats that easily determine how well a player is offensively. All three have different meanings, but share an equally important role. Also, they can deviate just based on the position that the person plays. Second basemen are more likely to be known for their defense than their offense, and first basemen are vice versa. That’s why a second baseman who bats .240/.290/.370 and a first baseman who bats .285/.330/.460 are about the same because they are the averages for their position (note: those are just my estimates of a players batting based on position). Miguel Cabrera, of course, leads the three categories in the AL with a .362/.456/.683 batting stance. In the NL, it’s split in all three categories: Chris Johnson from Atlanta has a .337 batting average, the Reds first baseman Joey Votto has a .434 OBP, and Rockies OF Carlos Gonzalez has a .591 SLG. 

I’m not here to talk about offense. It’s all about defense in baseball, especially now (just look at the depressing all-star game). ERA is a huge stat for pitchers, but did you know that they track a pitchers opponent batting average, OBP, and slugging? 

Clayton Kershaw leads the MLB among qualified starters with a 1.88 ERA, but he also leads the MLB with a .184 batting average against (BAA). So for every 1000 batters he faces, 184 of them will get hits. This is why people can’t hit Clayton Kershaw. 

Although there is a strong correlation between ERA and BAA, some pitchers don’t correlate, which is something you have to watch out for. A pitcher can give up eight hits a game but not score any runs because he gives up more singles rather than home runs, or is good under pressure. Matt Moore from the Rays has a .212 BAA, but has a 3.41 ERA. This is because he’s given up 10 homers and much more extra base hits this year. It also doesn’t help that he has 10 wild pitches on the year either. Mike Leake has a 2.86 ERA, but a .254 BAA. Stop giving up hits, Mike!

BAA doesn’t count for walks, which can hurt an ERA by a lot while keeping BAA the same. Opponent OBP is just as important. Adam Wainwright is my favorite example. Wainwright, who has put up great numbers in his career but unfortunately was out for the season in 2011 due to injury (ironically, the Cardinals still won the World Series). Wainwright gives up hits, as shown by his .248 BAA, but rarely walks anyone, shown by his .279 opponent OBP. Stephen Strasburg, however, has a .206 BAA, but has a .277 opponent OBP. He can be wild, especially this year, making his opponent OBP almost the same as Wainwright but a much different K/BB ratio. 

Opponent slugging might be the most important one. A hit is a hit, but a home run is much different from a single. Both count as hits, but a home run is already a run, which skyrockets the ERA. A smaller opponent slugging means that the pitcher is giving up more singles than extra base hits, which is a good sign. Jose Fernandez just edges out Matt Harvey and Kershaw with a .269 opponent slugging. Mike Minor can put up a .227 BAA, but he has a .378 opponent SLG because he’s given up 15 homers this season. Luckily, most of them are solo shots, as he has a 2.87 ERA still. Yu Darvish is worse, having a .186 BAA, but because he’s given up 19 home runs, he has a .325 opponent SLG.

BAA, opponent OBP, and opponent SLG all have different meanings, but have the same importance. There’s also opponent OPS, which combines the opponent OBP and opponent SLG. There are strong correlations with ERA here, but might even have more importance. It is a good way to discover a players value, and where they can improve on during pitching.

Email me at statsbuddy42@gmail.com for any questions/comments/concerns.

-Evan Boyd