FanGraphs Spotlight: Plus Stats

Writing a book is a Herculean task to begin with, and in my inimitable way, I made it even harder when writing my 2017 book on the Hall of Fame, The Cooperstown Casebook, by challenging myself to compose concise 200–250 word summaries of the 220 major league players who were enshrined at that point as well as a few dozen past, present, and future candidates. My goal in doing so was to give the reader a thumbnail guide to these players’ careers while shining some fresh light on even the most familiar ones using advanced statistics. I had no shortage of options, but even so, I wish I had all the tools then that I do now. Here I’d like to highlight one of them as part of our series on useful site features you’ll find at FanGraphs.

Consider the case of Dazzy Vance, a colorful and dominant right-hander who made his name with the Brooklyn Dodgers in the 1920s and ’30s. Vance was 24 years old when he debuted with the Pirates in 1915, but a variety of arm troubles limited him to just 33 major innings through his age-30 season. Finally pain free after elbow surgery (probably to remove bone chips), he resurfaced with Brooklyn in 1922, and on the strength of his combination of a blazing fastball and a sharp overhand curve “with a sweep that would shame a windmill,” as one writer described it, he led the NL with 134 strikeouts that season, and proceeded to repeat the feat in each of the next six seasons as well. His 262 strikeouts in 1924 was the highest total by any NL pitcher besides Christy Mathewson in the 1901–1960 span, and the highest by any pitcher in either league between the start of the Live Ball era (1920) and the United States’ entry into World War II (1941).

While I had enough confidence in my research to lead Vance’s Casebook capsule with, “Relative to his league, Vance struck out batters at a higher rate than [Nolan] Ryan, [Roger] Clemens, [Pedro] Martinez — any of them…” I worried that by explicitly quantifying his skill in this area that I’d either open myself to error or make even more work for myself, since the temptation was to go into further detail on the subject and perhaps calculate such data for every enshrined pitcher. Little did I know that within a year of the book’s publication that I would not only join the staff of FanGraphs but propose the creation of a leaderboard to tackle such questions with a few easy clicks.

The feature, which we call “+ Stats” or “Plus Stats,” launched in April 2019. Like wRC+ or OPS+, the + is shorthand for an index stat with a baseline of 100, where 120 represents a performance 20% better than average and 80 a performance 20% worse than average. The formula, as Bill Petti defined it while thinking along similar lines here at FanGraphs in 2012, is K%+ = [(Pitcher’s K% / League Average K%) * 100]. Unlike wRC+ or OPS+, our basic plus stats for pitchers and batters are currently not park-adjusted, but they’re still handy for comparative purposes — particularly across eras for rate stats that have varied widely over time. You can find them on our individual and team leaderboards, using the “+ Stats” button under the Stats tab. Here it is, highlighted in green:

That’s a leaderboard showing the 2023 season’s top 10 pitchers by K%+ using a 50-inning cutoff. You can of course choose a range of seasons (split or combined) or custom dates, and define your innings or plate appearance minimums, just as you would for most of our other stats. To get back to Vance, it turns out that he’s not just the leader in K%+, he’s the runaway leader, the only pitcher with more than 600 innings who has a rate at least double that of the league:

Vance is well ahead of some more familiar and modern kings of the K, such as Ryan, Randy Johnson, Sandy Koufax, and Bob Feller. Meanwhile, Billy Wagner, who just missed being elected to the Hall of Fame in January, has the third-highest rate at that cutoff — the second-highest if I raise the floor to 800 innings. For the first eight years of Wagner’s Hall candidacy, I was able to report that his 33.2% strikeout rate was the highest of any pitcher with at least 800 innings, but last year Kenley Jansen reached that threshold and is now ahead at 35.9%, while Aroldis Chapman has gotten his career back on track and is at 698 innings with a 40.3% rate. Relative to his league, Wagner still has the edge on Jansen, and Chapman will have to avoid regression and attrition over the next couple of seasons if he’s to supplant him.

Here’s a custom leaderboard I built, again ranking pitchers by K%+ but also showing their raw strikeout rates and totals as well as some other useful stats, this time with a 1,000-inning cutoff:

With this tool, you can see that while the Big Unit struck out batters at more than twice the rate of Lefty Grove, their rates relative to their respective leagues are very close. Via the BB%+ column, you can also get a sense for which pitchers were the wilder ones from this group; in this case higher numbers are bad, and we can see that Ryan’s walk rate was 46% worse than average. If you sort the table by total strikeouts, you can see that among the 19 members of the 3,000 strikeout club, Greg Maddux (100) got there with a league-average rate over 5,008.1 innings and Phil Niekro (105) was pretty close to average, with Ryan and Johnson at the other end of the spectrum.

We can use these tools on hitters as well. In 2019, when Jeff McNeil was tearing up the league, I went looking for other players with similarly high batting averages and low strikeout rates — that is, AVG+ and K%+ — relative to their leagues, first among his contemporaries, and then historically. Here’s what the full interface for such a leaderboard looks like:

For the table I built to compare McNeil to other hitters, I actually had to build two leaderboards, then join them together in Excel and filter the results to find the players in that “family” of performances:

The Plus stats have been hiding in plain sight for nearly five years now. We’re planning to include them on our player pages in the not-too-distant future, which should raise their profile a bit, and to add a few other rate stats into the mix. They’re fun to play around with, and serve as a great example of our developers’ ability and willingness to add new tools to our arsenal — and to yours. The best way to support the further development of such tools, and to support the site in general, is with a FanGraphs Membership. If you haven’t already joined, we hope you’ll consider it. And if you have joined, in addition to accepting our profuse thanks, please consider renewing or even sharing the bounty of what we have to offer with a gift subscription for a friend.