The past couple of weeks, I’ve written about how quality of defense and quality of opponent affects a hitter’s stats. This week and next, I’m going to do the same for pitchers. Today, I’ll be looking at how much a pitcher’s numbers change when facing different calibers of offense.
To study the effects of the opposing team’s offense on a starting pitcher’s effectiveness, I’m going to look at all regular season games played since 2002 and compare how pitchers fared against offenses of varying quality. To measure offensive quality, I’m using end-of-season runs per game.
I’m only including pitchers that started every game of the season (i.e. no relief appearances) and will be comparing their full-season stats to each individual start they made against each type of offense.
Offenses have been broken up into several buckets based on how far above or below league average they were in that particular year. The top bucket belongs to offenses that scored at least 30% more runs than league average, the next bucket to offense that scored runs between 20% and 30%, and so on. While the actual runs per game change slightly every year (and were accounted for in the study), here is the average runs per game for all years:
Here are the results of my study:
We see here that offense, as we would expect, has a large impact on a pitcher’s stats – perhaps even larger than we might imagine. Of the four stats that matter to participants in FanDuel’s standard MLB Salary Cap 35k contests, offense has the greatest impact on a pitcher’s win total. A pitcher will win 20% more games against a terrible offense than he will against one that’s merely average. And if we’re trying to decide between a pitcher facing a terrible offense and one facing a terrific offense, the pitcher facing the terrible offense has a 38% win advantage. That’s enormous! He’ll also allow 31% fewer earned runs and pitch 8% more innings when facing a poor offense over a great one.
Where we begin to see some strange results is when we look at strikeouts. Yes, facing a bad offense is better than facing a good offense when it comes to strikeouts, but it’s not as clear-cut as it was for the other stats. Can you guess why?
Strikeouts – a different beast
As you may have guessed, just because a team strikes out a lot doesn’t necessarily mean they’re bad. Because strikeouts correlate with home runs and walks (positive outcomes), a team that strikes out a lot will likely also be hitting home runs and drawing walks. If we’re playing the matchups and we want to know which pitchers are most likely to receive a strikeout boost, we need to look at the offense’s actual strikeouts instead of overall quality:
Guess what? Pitchers strikeout more batters when facing teams that strikeout a lot in general! Yup, pretty obvious, but it’s nice to see exactly how large the effects are. Against a team that strikes out 30% more than league average, a pitcher will strikeout 14% more batters than he usually does and 21% more than if he were facing a team that rarely strikes out.
Here’s the part where I put everything together and see what it all boils down to. This table shows exactly how great of an impact these effects have on your FanDuel team. This table lists the overall points per day a pitcher would produce against each type of offense, followed by the approximate FanDuel dollars those points would translate to (using a basic regression equation I created).
What we see here is that the difference between a pitcher facing an elite offense and a terrible offense is nearly $1500 FanDuel dollars. Obviously, that figure is enormous and tells us that match-ups have to be taken into consideration if we hope to be successful at FanDuel. In fact, aside from a pitcher’s own skills, the offense he’s facing ought to be the biggest consideration when deciding whether or not to pick him.
Like the past couple weeks, this study was conducted knowing who the good and bad offenses would be for the year ahead of time. At the start of a season, we can’t be certain which offenses are elite and which are awful, but we can make some good guesses. The Pirates, Padres, Rays, and Twins are pretty good guesses to be cellar dwellers this season, while the Yankees, Rangers, Phillies, and White Sox figure to be among the elite.
Derek Carty’s work can also be found at The Hardball Times Fantasy and DerekCarty.com. He has previously had his work published by NBC’s Rotoworld, Sports Illustrated, FOX Sports, and USA Today. He is the youngest champion in the history of LABR, the longest-running experts league in existence, and is a graduate of the MLB Scouting Bureau’s Scout Development Program (aka Scout School). He welcomes questions via e-mail, Facebook, or Twitter.