Statcast data has become a passion of mine over the last year. During the season, I wrote a weekly piece titled “Statcast Trends,” where I scoured the data to find players that were trending up or down. I also published a series titled “How To Use Statcast Data” earlier this offseason. Over the next several weeks, I will be using Baseball Savant’s expected stats to look at some players who over or underperformed actual production. Today, we will look at players with expected home run totals higher than their actual output.
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When looking at expected stats, especially one like xHR, you likely have questions. Is expected home run rate stable? Is it predictive of future success? Do some players consistently outperform xHR rates? These are all great questions and ones that are worth exploring to determine whether this is a viable stat to use.
Ben Clemens from Fangraphs did a study that found xHR to be predictive from the first half to the second half of the season. The study looked at the first and second half xHR rates from 2017 to 2019. The r-squared for the correlation was .465, meaning 46.5 percent of the variation in second-half home runs rates can be explained by first-half home run rates. The reliability of expected home run rates was also found to have a .642 r-squared correlation. Overall, I think this study shows that expected home runs is a statistic that is stable with also some predictive qualities.
Expected Home Runs
Baseball Savant’s expected home run leaderboard is an awesome new feature on the site. The leaderboard shows the players actual home runs, no doubters(a home run at every stadium), mostly gone(a home run at eight to 29 stadiums), and doubters(a home run at seven or fewer stadiums). Statcast uses the formula of ballparks a home run would have been gone at divided by 30 to calculate expected home runs. For instance, if Corey Seager hits a ball that would have left the park at 16 stadiums; his expected home runs would have been put at .53. Any batted ball that would have been a home run in at least one stadium gets registered as an expected home run, even if it is just one out of thirty.
It is important to note that environmental elements are not factored into this. Elevation, wind, weather, and other factors do not matter. It would be interesting to see if they can incorporate factors like that in the future. Stats on Baseball Savant for expected home runs are for both regular and postseason combined.
Let’s check in on some players who underperformed their expected home run total and see if we can expect a higher power output in 2021.
Expected Home Run Underperformers
Garrett Hampson, Colorado Rockies
HR/xHR: 5/9.4
How appropriate, the Garrett Hampson plugs live on. It is a running joke on the Fantrax Prospect Toolshed Podcast to fit Hampson in every episode. Eric Cross and I are big fans, despite the Rockies’ inability to play him consistently. Hampson did muster 184 plate appearances last season, hitting five home runs and stealing six bases. The overall stat line was not pretty as Hampson slashed .234/.287/.383.
Despite the struggles, Hampson was the largest underperformer in xHR with an expected number of 9.4. If he actually hit nine home runs last season, it would be interesting to see how he was being evaluated for the 2021 season.
Three of Hampson’s five home runs came within a two-game span in September. He also posted a strong September in 2019, slashing .333/.371/.561 over his final 15 games. He also hit five home runs and stole seven bases over that span.
Hampson does have a solid hit tool and great speed. The power has always been a question, but it has come in spurts throughout his career. He also just turned 26, so better days could be ahead if the Rockies are willing to give him regular playing time.
Christian Walker, Arizona Diamondbacks
HR/xHR: 7/11.3
I have been a big fan of Christian Walker since his days at the University of South Carolina, where he helped lead the team to two national championships. He was one of the most prolific hitters in College World Series history. Walker never took off in the MLB but was finally given a fair share of playing time with the Diamondbacks in 2019, seven years after being drafted. He rewarded the team by hitting 29 home runs, stealing eight bases, and slashing .259/.348/.476.
Walker gets undervalued at a shallow first base position, despite solid seasons in 2019 and 2020. He improved his batting average to .271 in 2020 and hit seven home runs, which still leaves plenty to be desired. However, Walker did come in right behind Garrett Hampson in xHR with 4.3 more than his actual output.
11.3 expected home runs is an encouraging output for Walker. It gives hope he can increase the power output in 2021 and be a 30 home run threat again. At his current ADP of 184, Walker is a buy for me.
Fernando Tatis Jr., San Diego Padres
HR/xHR: 19/22.2
Fernando Tatis Jr. was one of the best hitters in the game in 2020, hitting 17 home runs and adding 11 stolen bases. He slashed .277/.366/.571 and was the number two fantasy player according to Razzball’s Player Rater. As if he was not good enough, his statcast expected numbers were off the charts. With the highest average exit velocity, hard-hit rate, and barrel rate in baseball, it is no surprise that Tatis had a high xHR total.
He was the third-largest underperformer, and between the regular season and playoffs, Tatis had 22.2 expected home runs compared to his 19 actual. Only Marcell Ozuna had more “no-doubter” home runs that would have left any ballpark. Tatis had 14, while Ozuna had 17.
You already knew Tatis was good, but the expected stats think he can be even better. Steamer sees that, as they project him for 39 home runs, 26 steals, and a .286 batting average. Those are the makings of a number one overall fantasy asset, and Tatis is more than capable of doing it.
Jorge Soler, Kansas City Royals
HR/xHR: 8/10.7
Jorge Soler broke out in a big way in 2019 as he hit 48 home runs and drove in 117 runs as he played all 162 games with the Royals. Some touted that he was a better version of Giancarlo Stanton for 2020. The season was not kind to him as he struggled with an oblique injury that could have lingered all season. Oblique injuries typically zap power and affect a hitter’s ability to swing the bat. This could have been the case with Soler in 2020 as he hit just eight home runs, and his batting average dropped to .228.
The good news is that Soler hit the ball extremely hard and barreled it at a high rate. His statcast data was actually better than 2019, but the results just were not there. Soler did post 10.7 expected home runs, which is an encouraging sign. Assuming he gets healthy during the offseason, there is no reason to believe Soler cannot get back to his high home run output. Steamer projects him hitting 33 home runs, which is a great value at his current ADP of 148.
Adalberto Mondesi, Kansas City Royals
HR/xHR: 6/8.5
The Royals speedy shortstop, Adalberto Mondesi, is one of the most polarizing players in Fantasy Baseball. He has some of the worst contact rates in the league and strikes out at a high clip, making him a volatile player. Mondesi was so dreadful in July and August that many dropped him in redraft leagues. Outside of eight steals, Mondesi hit zero home runs and was slashing .186/.211/.240 through August 31. You can see why many fantasy players were dropping him.
The script was flipped over the final month of the season, though. His bat came alive, leading to six home runs, 16 steals, and a .356/.408/.667 slash line. After the dreadful start, he still finished as the 17th best player according to Razzball’s player rater.
Mondesi did make strides in his average exit velocity, launch angle, and hard-hit rate. His expected home run total was also 8.5, which is encouraging. Steamer projects him to hit 21 home runs and steal 54 bases in 2021. If the power is legit and Mondesi can get on base at a decent clip, he will be a high-end asset for Fantasy Baseball.
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