Jays From the Couch writer breaks down the reasoning for using more advanced stats when evaluating players
For a while now, I’ve wanted to put to words my reasoning for rarely ever using the popular triple slash line in my posts. I’m not entirely certain whether anyone cares, but if even one person takes something from it, I’ll be happy.
First things first, statistical snobbiness is not among my reasons. If a batter’s AVG/OBP/SLG tells you what you want to know about them, then more power to you. We’re each entitled to enjoy baseball and baseball statistics in whichever ways we want.
For me, the message each of those stats is trying to convey is conveyed more clearly and more effectively by other, fairly straightforward stats. In particular, I like to focus on a batter’s walk rate (BB%), strikeout rate (K%), isolated power (ISO), batting average on balls in play (BABIP) and weighted runs created plus (wRC+).
In a nutshell, I think the three slash line stats are trapped in a sort of no man’s land between being useful by providing specific information and being useful by providing general information. In contrast, the five stats I like to use excel at one or the other.
The first four I mentioned are great at providing nuanced information. A batter’s walk and strikeout rates tell me how often the batter walks and strikes out. A batter’s ISO tells me how many extra bases they earn per at-bat, on average. A batter’s BABIP tells me how often they’re able to turn a ball in play into a base hit.
These four stats split a batter’s overall performance into four clear and (relatively) mutually exclusive parts, aside from doubles and triples being counted by both ISO and BABIP. They tell you about some specific part of a batter’s performance, connecting roughly to the three general aspects of hitting: plate discipline (BB% and K%), power (ISO) and contact (BABIP).
[While BABIP is most widely used as a luck indicator—with deviations from .300 assumed to represent good and bad batted ball luck—the fact remains that good contact hitters run a much higher BABIP than poor contact hitters. Since 2010, Christian Yelich leads major leaguers in BABIP with a .359 mark, while Mark Teixeira runs last with a .246 mark (among 291 batters with 2000+ PA from 2010-18).]
In contrast, neither AVG, OBP or SLG focus on one thing. A strong AVG might be the result of a low K% or a high BABIP. A strong OBP might be the result of a low K%, high BABIP or high BB%. This lack of clarity has important effects on a fan’s ability to understand what’s going on with a player.
For example, particularly at the MLB level, a sub-.200 AVG caused by a low BABIP is a lot less problematic than a sub-.200 AVG caused by a massive K%, as BABIP can be volatile in small samples. Take Aledmys Diaz. In March and April, he ran a .183/.230/.354 line. My main takeaway from these stats is that he wasn’t really producing that month. My only other takeaway, after I calculate his .171 ISO by subtracting his AVG from his SLG, is that he was hitting for average power, which is good.
On the other hand, Diaz’s 3.4% walk rate, 14.9% strikeout rate, .171 ISO, .169 BABIP and 51 wRC+ that month tell me everything I need to know. He didn’t produce (54 wRC+), but he was running one of the lowest BABIP in the majors, so bad luck is a likely cause. Positively, he had a good strikeout rate and hit for above-average power, though he walked less often than most.
This looked like a guy who was primed for a breakout. Since May 1st, Diaz has maintained a 4.4% walk rate, 12.5% strikeout rate, .201 ISO, .278 BABIP and 111 wRC+. While he’s improved in terms of all of his stats, the biggest improvement by far is in his BABIP.
Aaron Judge is an interesting case study in the fogginess of AVG. He ranks 5th in wRC+ this season, with a 156 mark (min. 250 PA)—thanks to his contact skills (.377 BABIP), power (.263 ISO) and ability to take a walk (15.2%). However, he only ranks 48th in AVG (.285) because it doesn’t account for his latter two skills.
Moreover, he and Adam Jones are about as different a .285 hitter as there can be. Jones runs a K% (15.5%) and a BABIP (.316) that are both a little better-than-average. Judge is a bit more extreme in profile, running the league’s third-highest BABIP and 12th-highest strikeout rate.
A strong SLG, in spite of the name, doesn’t necessarily indicate a player is hitting for power. It usually does (SLG and ISO are highly correlated), but, like a strong AVG, a strong SLG can also be the result of a low K% or a high BABIP.
Jose Altuve, Jean Segura, Whit Merrifield and Lorenzo Cain are just a few examples of players who are currently running a well above-average SLG, but a well below-average ISO. The reason: they’re all running strong K% and BABIP, which drives up their total number of bases (and SLG), in spite of their limited power.
So, while there’s nothing wrong with analyzing a batter’s SLG (or AVG or OBP), the other four stats offer much more nuance, if that’s what you’re looking for.
If, instead, you’re looking for general information about a batter’s quality, none of the slash line stats are as effective as wRC+. The general usefulness of AVG is undercut by the fact that it doesn’t account for a batter’s ability to get walks or hit for power (see Aaron Judge). OBP is a little better, but still leaves power out of the equation. SLG does account for power, but leaves out walks.
Aaron Judge ranks 48th in AVG, 10th in OBP and 15th in SLG. Using these three stats alone, it would be tricky to make the case that he’s a Top 5 hitter. However, by wRC+, he ranks fifth in the majors behind Mike Trout (190), Mookie Betts (186), J.D. Martinez (181) and Jose Ramirez (174).
wRC+ accounts for every positive outcome (BB, HBP, 1B, 2B, 3B and HR) a batter can attain. While OPS (OBP + SLG; sometimes included as a fourth slash line stat) does so as well, wRC+ assigns values specific to each outcome (based on the relative run production of each), leading to better precision. As FanGraphs puts it, “OPS is asking the right question, but we can arrive at a more accurate number quite easily.”
wRC+ also accounts for park and league factors, adding to this precision. Best of all, wRC+ is expressed in a way that makes it super easy to understand how a batter’s performance compares to other players. A league-average batter produces a wRC+ equal to 100. Every point above 100 implies that a batter is one percent more productive than that league-average batter. The inverse applies to each point below 100.
Thus, a batter with a 120 wRC+ is 20% better than league average and can be considered good, with no other information. On the other hand, if I’m told that a batter has an .800 OPS (or .283 AVG or .358 OBP or .437 SLG), I’d need to remember what the league-average for that stat is these days.
Then, I’d need to give some thought to the park and era they played in. For instance, batters playing for the Rockies rank 5th, 20th, 55th and 68th in terms of OPS this season (among 258 batters with a minimum of 250 PA). However, those batters rank 14th, 62nd, 125th and 133rd in terms of wRC+. Park factors matter.
So, while there’s nothing wrong with using OPS (or AVG or OBP or SLG), wRC+ tells you the same things and more. Similarly, while there’s nothing wrong with using AVG, OBP or SLG to think about a player’s specific strengths, none of these slash line stats match the detail offered by a batter’s BB%, K%, ISO and BABIP.
My concluding advice isn’t to throw away the triple slash line. Instead, just consider promoting these other useful stats to to the top of your toolbox. There’s plenty of room in baseball for all of them, just like there was when OBP and SLG joined AVG as key stats in the very recent past. The most important thing is that we’re all watching, thinking about and talking about baseball.
*Featured Image Courtesy Of DaveMe Images. Prints Available For Purchase.
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I’m an economics professor in the GTA whose lifelong love for the Jays was reignited by that magical August of 2015 and the amazing moments since.