wOBA – xwOBA vs. Defensive Metrics


For quite some time, wOBA has been used as a well-known, all-around statistic for measuring the output of a hitter. wOBA doesn’t treat the many different ways of getting on base equally. Instead, it gives credit to the hitter for the value of each outcome, whether that be a single, home run, or walk. For more information, FanGraphs goes more in-depth here.

With the emergence of Statcast, xwOBA has been introduced. xwOBA uses launch angle, exit velocity, and sometimes sprint speed of the batter to give an expected value of wOBA on batted balls. xwOBA can tell us at what exit velocity and launch angle the most meaningful outcomes are produced. That is important to know because we can now see if specific teams or players are underperforming, overperforming, or are performing as expected based on these two stats. wOBA and xwOBA are not in perfect correlation for hitters with at least 50 plate appearances in 2019, but they still have a very strong relationship (r = 0.918). As plate appearances increase, the two should eventually level out to be the same. At what amount of plate appearances that occurs at, I don’t know.

What I want to know is what goes into a team’s defense if they are allowing a larger xwOBA than wOBA. That would mean they are taking expected hits for the opposing team and turning them into outs. I got to thinking about this idea while watching the ALCS between the Tampa Bay Rays and the Houston Astros, specifically Game 3, and I have now had time to dive deeper into my initial question. The Rays put together a beautifully played defensive game while their offense seemed to struggle outside of Randy Arozarena.

In Game 3, the Rays pitching staff combined to give up an xwOBA of 0.337, but they only allowed a combined wOBA of 0.300. Their defense saved 0.037 points of wOBA from the Astros to take a commanding 3-0 lead. Read the rest of this entry »

Quantifying Rumor Mongering in the Baseball Media Ecosystem

In what feels like interminable scrolling of the internet this offseason waiting for something to finally happen, it occurred to me to ask, does any of this rumor-mongering actually tell us anything? It is certainly strange that we as consumers of baseball, a modified game of tag with hitting and throwing a ball, care so much about the internal machinations of billion-dollar organizations and the personal decision-making calculus of people we will never meet. Regardless of this peculiarity, I myself still spend hours a week wondering if George Springer would be willing to play for a team who doesn’t have a guaranteed home stadium for the foreseeable future and subsequently will be located in a foreign country in Canada.

This interest is what feeds the North American baseball media ecosystem and employs thousands of people, from reporters to web designers, social media managers to news aggregators, and many more. I wouldn’t necessarily argue that this content holds no value if it is biased or inaccurate, because the time we spend consuming this offseason content really just satiates our longing for baseball when we can’t watch our favorite teams live. But the question remains, does this content hold any predictive value, or are we just fooling ourselves?

This article is based on data scraped from MLB Trade Rumors, the leading aggregator of rumors around baseball, on December 9, 2020. I pulled the last 2,000 posts that each team was tagged in and analyzed what information we’re actually getting from reading and discussing the rumors and reports inside the baseball media ecosystem. To begin, we can observe the volume of rumors for teams by seeing how many days one would have to go back to reach a cumulative 2,000 posts. Read the rest of this entry »

Why a World Series Appearance Might Not Save the Rays in Tampa Bay

As Major League Baseball prepares for 2021, teams are bracing for another season of COVID-19 related financial problems. There will undoubtedly be a smaller-than-usual capacity of fans at ballparks nationwide, and depending on the municipality, there might not be fans at all. Teams are hoping 2021 is not as bad as 2020. According to an analysis by the Tampa Bay Business Journal, the New York Yankees missed over $437 million in expected income. Near the bottom of the list, the Tampa Bay Rays lost only $67 million in expected income.

But the pandemic affected the Rays in additional ways, some of which could impair the ability of the team to stay in Tampa Bay. As the Rays recently appeared in the World Series, it is important to explore how the pandemic could impact the long-term sustainability of baseball in Tampa Bay.

In 2019, the Tampa Bay Rays won 96 games and made the playoffs for the first time in six years. Their series versus the Astros was the Rays’ first postseason under Kevin Cash and their first since Joe Maddon and Andrew Friedman left the organization following the 2014 campaign. After three mediocre seasons, the Rays had increasingly improved under the radar of all but the most dedicated baseball fans. Read the rest of this entry »

The Best Catcher in Free Agency (Not Named Realmuto)

There are few things in baseball worth more than a star-level catcher. Playing a position that requires you to squat each day for a 162-game season makes for a lot of injuries and shortened careers, and the role of a catcher is so crucial between game-calling, baserunning control, framing, and blocking, that just playing your good defense and being pitcher-friendly will get you a long career no matter how horrible you are with the bat.

Fortunately for all teams in need of a receiver, the 2020 free agent market offers one of the rarest cases among the sport, a true five-tool catcher: J.T. Realmuto, the former Marlins and Phillies backstop, is available for his mere salary.

You want a steady bat, maybe with some thump? Realmuto walks in sporting a career .278 AVG, .455 SLG, and double-digit homers in each of his six “full” seasons in the league.

You need a reliable asset, one that punches the ticket and goes to work? He averaged over 130 games from 2015-19.

You need a rock-solid defender that can also help your guy on the mound? J.T. is there for you with a rocket arm (over 88 mph on his average throw) and a spotless fielding percentage, and while he’s behind the plate, he’ll steal strikes for your pitchers as a 95th-percentile framer does.

Heck, he’ll even run if you ask him to, dashing at over 28 mph, making him an 84th-percentile runner, an absurdity given his role on the field. Read the rest of this entry »

How Possible Is a Five-Homer Game?

A recent post in the Effectively Wild Facebook group sparked my curiosity. A poster named Tim wrote: “Record I’d like to see set that isn’t inconceivable: Player gets 5 HR in a single game.” That record is not inconceivable, because it has been accomplished at least five times in the minor leagues.

In fact, the professional baseball record is eight home runs in a single game, set by catcher Jay Clarke of the Corsicana Oil Cities in a 51-3 win over the Texarkana Casketmakers in a Texas League contest in 1902. The last minor leaguer to hit five homers in a single game was Dick Lane of the Muskegon Clippers in 1948.

Known Five-Homer Games
Date Player Team Opponent Outcome League HRs Hit
6/15/1902 Jay “Nig” Clarke Corsicana Oil Cities Texarkana Casketmakers W, 51-3 Texas League 8
5/11/1923 Pete Schneider Vernon Tigers Salt Lake City Bees W, 35-11 Pacific Coast League 5
5/30/1934 Lou Frierson Paris Pirates Jacksonville Jax L, 17-12 West Dixie League 5
4/29/1936 Cecil Dunn Alexandria Aces Lake Charles Skippers W, 28-5 Evangeline League 5
7/3/1948 Dick Lane Muskegon Clippers Fort Wayne Generals W, 28-6 Central League 5

But of course the poster was in all likelihood talking about the MLB record of four in a game, which has stood since 1894. But it was a commenter on the post that really piqued my interest. They simply asked: “Would a team really continue pitching to a guy who’s already had 4 HR in a game though?”

It’s a valid question to ask, and it set me down a rabbit hole of seeing just how many players had a plate appearance with four homers already in a game, and how those plate appearances went. Looking back at history isn’t necessarily the best way to predict future behavior, but it is a fun exercise if nothing else, because frankly, before conducting this research I had no idea how many players ever had a crack at a fifth home run. Read the rest of this entry »

How Much Value Is Really in the Farm System?

Everyone knows that a strong farm system is key to the long-term success of a major league organization. They make it possible for clubs to field competitive teams at affordable salaries and stay beneath the luxury tax threshold, but how much value can an organization truly expect from their farm system? How much more value do the best farm systems generate compared to the worst ones? I decided to take a closer look.


The first thing I did was gather the player information and rankings from the Baseball America’s Prospect Handbooks from 2001-14 and entered them into a database. I then found players’ total fWAR produced over the next six seasons, and I added them together to find the values that each farm system produced. I chose six seasons to ensure that teams wouldn’t get credit for a player’s non-team-controlled years, since the value produced would not be guaranteed for the player’s current organization. This method will reduce the total value produced by players that are further away from the majors, but the purpose of this analysis is to focus on the value of the entire farm system and not an individual player’s value over the course of their career.

Let’s look at the 2014 Minnesota Twins as an example. Below is a list of the thirty players that were ranked and the amount of WAR that each player has produced by season. Read the rest of this entry »

Challenging WAR and Other Statistics as Era-Adjustment Tools

This article is a casual version of my paper “Challenging Nostalgia and Performance Metrics in Baseball” published in Chance which showed, among other things, that wins above replacement (WAR) and the wide class of “versus your peers” statistics are incapable of accurately comparing players across eras. In particular, it was shown that WAR exhibits a very strong bias toward baseball players who played in earlier seasons. A collection of resources and an interactive web app within this framework can be viewed here.

How We Came To This Conclusion

In our research, we split baseball data into time periods and show that WAR includes players from the older era in its all-time rankings. Specifically, the older time period is defined by players who started their career in 1950 or before, and the newer group is defined by players who started their career after 1950. The split date of 1950 corresponds to the US Census that is closest to the integration of baseball in 1947. Prior to 1947, Major League Baseball was a largely all-white segregated sports league, but it slowly but surely integrated in America and the has steadily risen in popularity abroad. All the while, the world populations continue to grow as time progresses. Simply put, there are far more people in the baseball-eligible talent pool post-1950 than before.

We find that roughly 20% of the “realistic historic talent pool” belongs to the pre-1950 group. By “realistic historic talent pool” we mean the cumulative population of men ages 20-29 collected every 10 years arising from baseball playing countries (men ages 20-29 serve as a proxy for a concept of talent pool that is otherwise not well-defined). Before 1950, this population is basically just white American men. After 1950, this population includes all American men, as well as men from a plethora of baseball-playing countries. Read the rest of this entry »

A Rule Change Idea Too Fun for MLB

If you’re reading this, you are surely a baseball fan, and as such, you’re probably aware that Major League Baseball is putting lots of options on the table when it comes to rule changes to shake up the game and make it more interesting. We’ve already seen the intentional walk become automatic and the limiting of mound visits. MLB also reached an agreement with the Atlantic League to experiment with some other ideas, such as robot umpires, a three-batter minimum for pitchers, starting extra innings with runners on base, moving the mound back, and banning the shift. Some of these ended up being adopted in the majors on a temporary basis for the pandemic-shortened 2020 season and may end up getting implemented more permanently, depending on how the upcoming CBA negotiations go.

But I have an idea that I think is better than any of these. It’s a small rule change; but it would radically change the game. Too radical even for this change-happy commissioner, I think. And here it is:

On a ball in play, a runner who reaches home can decide to continue on to first base and keep running.

Now, before I explain why I find this rule change so appealing, let me first get the logistics out of the way. How could it be determined if a player has decided to go to first or not? For this part, it would have to operate the same as a batter running to first base. (To be clear, I don’t think it should be a force play at first base, though it would still be fun if it was.) Read the rest of this entry »

RE+: Factoring Player & Team Hitting Ability Into Run Expectancy and the True Value of a Stolen Base

There are 24 different “states” in baseball. The three bases can be filled in eight different ways, and there can be 0, 1, or 2 outs at any given moment. Each of these 24 base-out states has an expected run value associated with them. Each value represents the average number of runs that the team is expected to score by the end of the inning. These values change each season depending on the run environment, but they generally don’t vary much.

2019 Average Run Expectancy by State
STATE 0 outs 1 out 2 outs
000 0.53 0.29 0.11
100 0.94 0.56 0.24
010 1.17 0.72 0.33
001 1.43 1.00 0.38
110 1.55 1.00 0.46
101 1.80 1.23 0.54
011 2.04 1.42 0.60
111 2.32 1.63 0.77

Consider the following situation: Lorenzo Cain is on first base with two outs. Now consider two possible hitters, one being Christian Yelich and the other being Ryan Braun. According to the 2019 averages, the run expectancy in this base-out state was 0.24, regardless of the hitter. While both players had impressive seasons, Yelich is unquestionably the superior player at this point in time.

2019 Player Comparison
Player wOBA ISO
Ryan Braun .354 .220
Christian Yelich .442 .342

As a result of their differences, the run expectancy should be higher when Yelich is at the plate. Consequently, the benefit Milwaukee gets from Cain attempting to steal second base should be adjusted as well. Why is this the case? Given Braun’s inferior power and hitting ability, there is more to gain from Cain putting himself in scoring position, but more importantly, there is less to lose if he were to get caught. On the other hand, Yelich is much more likely to drive the ball. With Yelich at the plate, the increase in run expectancy from a stolen base is slightly smaller than if Braun were hitting. However, the decrease in run expectancy from being caught is significantly greater. This is why we need RE+. Read the rest of this entry »

An Extra Inning Runner Study

The 2020 season brought unprecedented rule changes, one of the most puzzling among them being the “extra inning runner.” Ostensibly in an effort to reduce the spread of COVID-19 and speed up play, commissioner Rob Manfred decreed that once a game progresses past the ninth inning, a runner would be placed at second base to begin the frame.

Manfred’s blatantly obvious motives turned baseball fans — a demographic notorious for their acceptance of changes to the national pastime — against it. If there is any defense to be made for the addition of the extraneous runner, it’s that shorter games helped save pitchers’ arms in what’s already been an utterly brutal season for pitcher injuries.

This seismic rule change also created a correspondingly large shift in how teams strategized after a game surpassed nine innings. Teams, even the more sabermetrically inclined among them, began to employ traditional tactics. In order to determine how clubs played with a free runner, I charted every extra inning of the 2020 season. Read the rest of this entry »