Author Archive

Predicting Hall of Famers with Machine Learning

The questions of who should and who will make it into the Baseball Hall of Fame have inspired countless debates, books, articles, and statistics. From the early days of statistical milestones like 3,000 hits, 500 home runs, and 300 wins to more advanced measurements like WAR and JAWS, and throughout baseball’s many eras, many have attempted to tackle the task. The discussion is more or less ongoing but peaks whenever a prominent player retires and during every winter ballot season. Innovations like the Hall of Fame Tracker have only added fuel to the fire.

I wanted to see if machine learning was up to the task of predicting who’ll get enshrined. I trained and evaluated a prediction model and used it to predict induction chances for current and recently retired players. I specifically wanted to see if I could get a sense of how some of the game’s younger superstars are doing, because who doesn’t want to talk about how good Juan Soto is?

In this article I discuss building and evaluating the model and show the predictions it makes. If you’re interested in the former, continue reading; if you’re interested only in the predictions, feel free to skip to the end. Read the rest of this entry »

Elieser Hernandez’s Improved Arsenal Makes Him a Rule 5 Pick to Watch

The Miami Marlins lost 105 games in 2019 under the shadow of their latest rebuild. For this franchise, it seems, hope is eternally just over the horizon. But like many rebuilds, the dispiriting results on the field hid some areas of promise.

In the Marlins’ case, people buzzed about some of their young arms. Sandy Alcantara got everyone the most excited with his 2.3 WAR, followed by guys like Pablo Lopez and Trevor Richards who could be called “serviceable’” which is a compliment for what’s essentially a quad-A team. (Before you boo me, know that I’m an Orioles fan.) Caleb Smith and Jordan Yamamoto also got some interest.

Other teams noticed. The Rays acquired Richards and Nick Anderson in the middle of a playoff run. The Diamondbacks did the same with Marlins hurler Zac Gallen. Down in the minors, hitters like Jazz Chisholm and JJ Bleday get attention alongside pitchers like Sixto Sanchez (what a fantastic name!) and Edward Cabrera.

But not many people got excited about Elieser Hernandez. I can understand why they didn’t: he’s not a household name. The Astros signed Hernandez in 2012 just after their much-heralded change in regimes and leagues. He bounced around their minors for awhile before the Marlins snagged him in the 2017 Rule 5 draft. Unless your name is Johan Santana (or maybe Dan Uggla), no one’s going to get excited if you’re picked in the Rule 5 draft. Heading into 2018, John Sickels gave Hernandez a C+ grade and ranked him 22nd among the team’s prospects.

After joining the Marlins, Hernandez was unspectacular in the minor leagues, posting a 21% strikeout rate and 10% walk rate across three levels. He fared much worse on a major league mound, with a 15.9% strikeout rate and 9.5% walk rate alongside a .337 xWOBA in more than 65 innings. Those disappointing stats contributed to a similarly disappointing -0.5 WAR. Read the rest of this entry »

Emilio Pagan Rides Improved Fastball to Breakout Year

Emilio Pagan made his debut in 2017 with the Mariners. He impressed somewhat as a 26-year-old rookie, notching a K-BB rate of 24.5% en route to an xFIP- of 93. Not bad. The Athletics traded for him that offseason, whereupon Pagan promptly did much worse. His strikeout rate dropped four points while his walk rate rose three. He also suffered from long-ball-itis and saw his xFIP- climb to a below-average 112.

The Rays then got ahold of him in the three-team Jurickson Profar deal with Texas. Pagan began 2019 in Triple-A but was called up in mid-April when Blake Snell fractured his toe. Three days later, Pagan was sent back down; two days later he was back in the bigs. All he’s done since then is help his team chase a playoff spot.

As the team’s nominal closer, Pagan has accrued 1.4 WAR, which ranks ninth among qualified relievers. Take leverage and innings totals away and his 1.63 WPA/LI ranks fifth. Baseball Prospectus and their DRA-based methodology agree he’s good. Among pitchers with a maximum of 75 innings pitched, Pagan’s 1.7 WARP ranks fifth.

Pagan’s been dominating hitters to the tune of a 30.6% K-BB rate, seventh-highest among qualified relievers. And when batters do put the ball in play against him, they’re not doing much. His .213 xWOBA against is the lowest in the entire sport among pitchers who’ve faced at least 50 batters. Read the rest of this entry »

Giovanny Gallegos Deserves More High-Leverage Opportunities

Making the 2019 playoffs was never a sure thing for the St. Louis Cardinals. With the Brewers returning most of the team that won the 2018 division and the Cubs returning most of the team that contended until the literal last day of the season, and with the Reds and Pirates qualifying as “interesting” at worst, every single thing needed to go right for the Redbirds in 2019. Unfortunately for them, entering play on July 6th, the team’s odds for a playoff berth sat at just under 28%.

Still, the team is just three games out of first place and half a game out of a Wild Card spot. They need every win they can get, which is why Mike Shildt should give Giovanny Gallegos more high-leverage opportunities. One of the newest Cardinals, Gallegos was part of the trade that sent Luke Voit to the Yankees last year. His name didn’t cause many eyebrows to raise; after all, at the time he had a just-okay K-BB% of about 20%. Voit’s performance in the second half easily overshadowed any mention of Gallegos’ name.

But 2019 is different. Gallegos now features a stellar 33.3% K-BB rate, behind that of only four qualified relievers: Josh Hader, Ken Giles, Will Smith, and Kirby Yates. (You may have heard of these guys.) He’s missing bats like never before, and when hitters do get the bat on the ball, they’re not doing much. While everyone and their little brother is hitting 20-plus dingers, Gallegos’ HR/9 rate dropped year-to-year. It’s not a fluke; his xWOBA fell from .304 last year to .250 where it sits now. This ranks 16th out of the 388 pitchers who’ve faced at least 100 batters. Read the rest of this entry »