If you’ve followed baseball over the course of of the past few seasons, you’ve probably noticed the new data available to us with the advent of Statcast. This has led to the development of new metrics to measure player performance, with xwOBA being one of the most notable. If you’re familiar with xwOBA, you have likely seen it used to examine the quality of contact made or induced by hitters or pitchers.

Today, I want to look at the pitcher side of things. While it is generally accepted that some pitchers are better at inducing weak contact than others, to this point, the baseball community is still working through the best ways to process the implications of the relatively new data available to us.  As Craig Edwards wrote yesterday on the main site, there isn’t a strong relationship between weak contact year to year.

Acknowledging all of this, I want to look at pitchers who have recently improved the quality of contact they have allowed. There are a couple assumptions to acknowledge here (included at the bottom of the following table). First, I am only looking at pitchers with over 1000 pitches in 2017 before the All-Star Game. Additionally, I am only including pitchers who have thrown 500 pitches since the All-Star Game.

My intent with this is to try to get a better look at starting pitchers, who have made more than a couple of starts, and remove relief pitchers. I have also limited the group to players who’s post All-Star Game expected wOBA is less than the sample average at the time of the break (this works out to be around .315, for reference). The last stipulation I have included is that I am only showing pitchers who have seen an improvement of .010 or greater in their expected results (10 points or greater). The reason for this is simple, I would rather show 25 results than 45.

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My favorite part of this year’s World Baseball Classic, aside from the baseball, obviously, was the television broadcasts’ frequent reference to players’ swing speeds. I was floored, even if only because I didn’t know (but should’ve known) we had the technology capable of measuring it. Regarding Major League Baseball and Statcast’s adoption of such a metric, a little birdy told me I shouldn’t hold my breath. Disappointed, I moved on.

Then yesterday, while fooling around in Baseball Savant’s Statcast database trying to diagnose the misalignment of Miguel Cabrera’s outcomes with his peripherals, I noticed the database query’s “sort by” function offered an option to sort by “estimated swing speed.” A quick Google search indicates to me the Statcast and MLB Advanced Media team(s) has (have) yet to formally announce this; sprint speed has been the more exciting recent development, apparently.

Not to me! I quickly got to work querying the data. I also quickly learned downloading the raw data files that underpin the swing speed summaries previously linked do not include swing speed, which is unhelpful. In other words, swing speed is not communicated to us from Baseball Savant’s organs on a play-by-play basis. I imagine this is by design. So, I was resigned to running a single query that summarized swing speed data at a high level: the average swing speed for every hitter with at least 100 at-bats in a given season, from 2015 through 2017.

Here’s what I found.

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This is a long one. I appreciate your patience in advance.

Mike Podhorzer, I and sporadic others have — but primarily Mike has — carried the torch on developing ‘expected’ metrics, such as xBABIP (expected batting average on balls in play), xHR/FB (expected home run-to-fly ball ratio) and xK% (expected strikeout rate), all and the rest of which can be found here. For the uninitiated, these xMetrics help describe how a hitter or pitcher should have performed based on various measurements of the events that unfolded and typically are more predictive of future performance than the original metric. They’re not perfect, but, like other advanced metrics, they give us a better understanding of player performance and ability.

Each metric — xHR/FB, xK%, etc. — has formulas for both hitters and pitchers, with the hitter metrics typically having stronger correlations than those for pitchers. Unfortunately, pitcher xBABIP has always eluded us. It’s inappropriate to repurpose hitter xBABIP for pitchers, but it’s because the model coefficients (weights) would be different, not because the theory underpinning the model is flawed.

That’s the problem, though: hard hits, line drives, infield fly balls — these all should affect a pitcher’s BABIP allowed. Our intuition begs it to be true. Yet there’s a resounding lack of evidence that suggest otherwise. The correlation between BABIP and hard-hit rate (Hard%), line drive rate (LD%) and infield fly ball rate (IFFB%), among others, borders on nonexistent:

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Yesterday, FanGraphs made public its splits leaderboard, which the authors have been able to test and refine in private for some time now. It’s an incredible tool. If you haven’t checked it out, you should. If you haven’t thanked Sean Dolinar for building it, you should. (If you have any preliminary feedback, leave it in the comments and I’ll pass it along.)

There are a seemingly infinite number of ways to cross-cut data in endlessly fascinating ways. Splits by handedness, situation by outs, situation by leverage, situation by defensive alignment (shift or no shift!) — the list goes on. But the thing that most interested me immediately was understanding the implications of more granular batted ball data.

Two tools I once refined/created — xBABIP and xISO — rely almost exclusively on Baseball Info Solutions (BIS) batted ball data. Yet they were limited in their capabilities because of the limited nature of the data: we knew each hitter’s contact quality (hard/medium/pull) and contact direction (pull/center/oppo) but now how the trios intersected. But, ah, the splits leaderboard.

The following tables depict the batting average on balls in play (BABIP), isolated power (ISO), and home runs per fly ball (HR/FB) in 2016 by each cross-section. Read the rest of this entry »

Updated Feb. 25, 2017

Aug. 16, 2016: Updated Alex’s xBABIP equation and added Andrew Dominijanni’s xISO equation.
May 23, 2016: Published.

Jump around in this post:
Hitter metrics: xBABIP | xISO | xHR/FB | xOBA | xK%
Pitcher metrics: xHR/FB | xLOB% | xK% | xBB%

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Do you frequently use RotoGraphs’ “X” (expected) metrics? Do you wish they were easier to find? Have you ever commented to ask if they could be added to the leaderboards or at least wished they were all located in one spot? If so, you may want to…

BOOKMARK THIS PAGE!

I don’t know if there will ever be a time when FanGraphs has a leaderboard devoted to “X” metrics. The fantasy analysts at RotoGraphs have taken a largely vigilante approach to creating descriptive and predictive expected metrics over the years. Moreover, each metric typically undergoes an iterative process by which we improve it when new data is made publicly available to the authors.

So, this is it. This is my best attempt, on behalf of RotoGraphs’ staff and at the polite and enthusiastic behest of its readers, to centralize the freshest versions of the relevant metrics the RotoGraphs staff most frequently cites. I have also built primitive Microsoft Excel-based calculators for some (but not all) of the metrics that crunch the numbers as long as you provide the appropriate inputs. It should save us all an extra minute or two and preserve our sanity a little bit.

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