Even the best statistics, things like wRC+, are imperfect. You can’t take wOBA as a perfect measure of truth or be certain that FIP is a perfect estimate of pitcher performance. In many cases, they may be the best we have, but we acknowledge the limitations. While it’s true that even our favorite metrics have flaws, that doesn’t mean that we should give equal considering to extremely flawed statistics.
This post will be the first in a series, scattered across the offseason months, that demonstrates the serious problems associated with some of the more popular traditional metrics. Many of you are well aware of these issues, but plenty of people are reading up on sabermetrics for the first time every day and our goal here is to create a comprehensive guide that helps everyone get the most out of everything we have to offer. Part of that puzzle is explaining why you might not want to look at things like batting average, RBI, and wins. Today, we’ll start with Runs Batted In (RBI).
RBI is one of the most famous baseball statistics and measures the number of runners who score due to your hit, walk, sacrifice, or fielder’s choice. Generally speaking, a 100 RBI season is considered worthy of admiration and the notion of “driving in runs” or being and “RBI guy” is highly valued.
There are essentially two ways to approach the problem with RBI as a statistic. First, there is very little evidence that timely hitting or clutch hitting is a skill separate from regular hitting. Second, even if those are real skills, RBI is a very crude way to measure that skill and you should use something else. We’ll consider each of those in turn.
A knack for driving in runs?
Before we go any further, we need to decide if we value getting hits with men on base, particularly with men in scoring position. Should it matter if a hitter has a .350 wOBA with most of his hits skewing toward RISP situations or a .350 wOBA with most of his hits skewing toward bases empty situations. Is one player better than the other?
In order to make the argument that the RISP hitter was better, you would have to argue that he was able to influence the timing of his hits. To date, there is very little evidence that this is a unique skill and there is little to support the idea that certain hitters “know how to drive in runs.”
Clutch numbers and offensive metrics with men on base or men in scoring position correlate very poorly from year to year and you are much better off judging a player based on how he performs in general rather than how he performs in “run producing situations.”
But part of this is philosophical and a matter of preference. Do you want to give credit to hitters who happen to collect a lot of well timed hits? When it comes to determining retrospective value, it might make plenty of sense to do this.
You have to decide if you want to judge a player by his context neutral performance or by how he performs given the opportunities he’s given. If you care about context neutral performance, our discussion is over because RBI are conditional on your teammates (other than RBI via HR) by definition. There have to be men on base for you to drive them in. But if you do have some interest in context dependent numbers, we need to move forward.
Does RBI tell you what you want to know?
Let’s make the assumption that we do care about a hitter’s production in the context of his environment and we want to measure hitters based on what they do with the cards they are dealt. Does RBI do a very good job of that?
You get an RBI if your hit/walk/etc sends a runner to the plate, but some RBI are easier than others. With a man on third and no outs, it’s quite easy to drive the runner home, but with a man on first and two outs, it’s much more difficult. Importantly, not all players have the same number of PA with runners on each base. Let’s look at an example from 2014:
|Player||PA||Runner on 1B||Runner on 2B||Runner on 3B|
Castellanos came to the plate with runners on first and second more often than Trout and a runner on third the same percentage of the time. Obviously, Trout was better in his opportunities than Castellanos, but the illustration suggests that even without considering the number of outs, some hitters have more chances to drive in runners than others.
And that’s a problem. If you get to bat with more men on second and third, you’ll have more RBI even if you have identical rate stats across the opportunities that you do have. It’s not right to reward a hitter just because the quantity of his RISP situations is high. You might want to reward a hitter for their performance in each type of situation, but surely not for the number of those situations.
But it goes beyond that. Maybe we’re all capable of mentally adjusting for the idea that certain hitters in better lineup spots on better teams will have a higher number of chances and we don’t really mind that Trout has more RBI than someone like Brandon Crawford, but there’s another serious issue that adds more haze to the whole endeavor.
You can contribute to run scoring even without being the hitter who plates the runner. Imagine you’re batting with a man on first base and one out. You rip a clean single to the right center field gap and the runner advances to third base. You moved him up two bases. Then the next hitter hits a routine fly to center field and the runner scores on a sac fly. Who gets the RBI? The guy who hit after you did, even though one could easily suggest you played a bigger role in driving that run in. Not only did you register a hit, but you advanced the runner two bases rather than one. RBI gives you no credit whatsoever.
And this runs counter to the idea of situational hitting. The guy who hit the sac fly “drove him in” but you did more heavy lifting. If he had been standing on second or third base when you came up, your hit would have scored him. Instead, the next hitter claimed the RBI in less impressive fashion. It’s not just about the number of chances, it’s about the collective action of run production. Even if you want to evaluate hitters in context, you have to look at every step along the way, not just the one that comes at the end.
This makes RE24 a useful alternative if you want a context dependent number.
So while there isn’t really evidence that hitting with men on base is a skill independent of your regular abilities, the more important reason why RBI isn’t a good measure of offensive performance in any way is that it doesn’t even capture the performance it means to. Batters do not have equal opportunities to collect RBI. In fact, in some cases the the stars can align and hitters can rack up tons of RBI despite performing quite poorly, simply because they were given very favorable circumstances.
Importantly, this is not simply a small sample size issue. While better hitters have more RBI on average the relationship isn’t particularly strong even over entire careers.
Generally speaking, RBI is not a useful measure of offensive performance. It may be useful as a way to explain the events of a game, but a player having 100 RBI and another having 75 RBI tells you almost nothing about those two players and the seasons they had. Generally, it’s hard to rack up huge RBI totals while having a horrible season, but there are much better stats available, even if you want one that rewards hitters for advancing runners. The key is you have to reward them for all runner advancements, not just the ones that lead to runs.
Questions about RBI and its problems? Ask in the comments!
Neil Weinberg is the Site Educator at FanGraphs and can be found writing enthusiastically about the Detroit Tigers at New English D. Follow and interact with him on Twitter @NeilWeinberg44.