Written by: James Schiano (@FreePeteAlonso)

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Just more than a quarter of the way through the season gives us a level of data that is beginning to stabilize. Most individual stats need more games to be fully trusted, but league wide trends have so many data points by now that they’d be nearly impossible to buck.

One of the most obvious changes this season is the death of the fastball count and dwindling fastball use in general. If you use Baseball Savant to gather sabermetric data, I’m sure you’ve noticed that most pitchers’ Pitch% data looks like this:

And hitter’s like this:

Focus on the far right side of the red and blue trend lines. Fastballs are being thrown less and breaking balls are being thrown more. Sure, using the best hitter and pitcher in the league doesn’t make a trend, but Eno Sarris wrote a great article last week detailing this shift in most pitcher’s approach and how hitters are responding to it. Breaking balls are on the rise, but more specifically Slider% continues to rise.

It seems as if this is only the beginning of the age of the slider. In turn, I wanted to figure out which hitters had already shown a strong ability to hit the offering. Using Savant, I looked at all players’ xwOBA vs sliders since the beginning of 2018, set the minimum number of total pitches seen at 400, and came out with this chart. Five names stuck out to me.

Note: the names pinpointed above (and below) are five of the top seven hitters versus the slider. The other two points that stick out are Mike Trout (we know he’s good) and Jim Adduci (we know he’s not).

 Pete Alonso

What more can be said about my man Pete? He is the focus of my Twitter handle, the apple of my eye and basically the only reason my favorite team can win a ballgame this season. I shudder to think about where this Mets team would be without Alonso in the fold.

On top of it all, the first baseman has the highest xwOBA versus the slider in all of baseball by a pretty wide margin. He’s hitting .385 against sliders with an average Exit Velocity of 96.6 MPH while seeing it less often than the fastball and sinker. With his wide, crouched stance, Alonso is a textbook low-ball hitter and should continue to mash if pitchers keep pounding the lower half of the zone.

Yandy Diaz

If you follow me on Twitter, you would have seen me hyping up Diaz a little way back in March (and Ray included him in his high-value active player list this season). Any baseball fan’s ears should perk up whenever the Tampa Bay Rays agree to a trade or sign a player as they are currently operating on an extremely high level as an organization. So last winter when the Indians shipped Diaz south, one had to figure the Rays knew how to tap into some of the power the 6’2, 220 lb. Diaz couldn’t seem to wrangle.

He’s doing just that, knocking 9 of his 10 career home runs through just 180 plate appearances this season (1 HR in 299 PA previously), and a big reason why is his ability to crush sliders. A .622 xSLG and 92.3 MPH Exit Velocity against sliders is off the charts. His average launch angle of 4.8 degrees still leaves a lot to be desired, but it’s sitting at a lofty 13 degrees off sliders. I’m as big a believer in Diaz and think we see continued growth from of the Cuban slugger.

Matt Olson

It’s easy to forget about a guy when he breaks a bone in his hand overseas at 4:00 in the morning before 28 of the 30 teams have played a game, and that’s just what happened to Olson. One of the hottest names from draft season, I’m sure he can currently be found on the waiver wire in shallower leagues with only a handful of games under his belt in 2019. This is a player who was in the 98th and 99th percentile in Hard Hit% and Exit Velocity respectively in 2018 on top of playing gold glove level defense at first base. He makes the perfect buy low asset in dynasty leagues.

He slugged .488 on sliders last season and showed signed of positive regression with a xSLG of .528. It is troubling that his Whiff% currently sits at 55.6% against the pitch, but it was only 37.5% last year and should sink to similar levels as his sample grows.

Franmil Reyes

I love Franmil. It’s infectious when there’s a guy out there who clearly loves the game, specifically his bat, as much as Reyes.

Franmil Reyes kissing his bat. #Padres 😘 pic.twitter.com/25b5d3HPwM

— Lance Brozdowski (@LanceBroz) May 21, 2019

Fellow staff writer Mac Squibb wrote extensively about Reyes way back in February and boy was he right about this breakout. The dude is ripping the cover off the ball to the tune of 15 home runs in only 50 games. Moreover, his 18.4% barrel rate currently sitting in top three percent of the league shows that the power is no fluke.

The power output is even more impressive considering Reyes sees sliders 24.5% of the time, more than 6% higher than the league average of 18.2%. Unfortunately for opposing pitchers, he hit .298 with a 94.8 exit velocity versus them in 2018 and he’s up to his old tricks so far this season. If this trend continues, Reyes’ notoriety as one of the most prodigious sluggers in baseball should grow.

J.D. Davis

Everyone knows the Mets had a busy offseason. While Wilson Ramos and Robinson Cano have struggled thus far, Davis has been a pleasant surprise at the dish. He has showed off his immense power in a very limited role thus far, stroking 5 home runs and 6 doubles in just 125 plate appearances. More importantly, he’s cut his Chase% from 28.7% to 23% which has helped him strike out less than ever before.

A huge reason for this improvement are his ridiculous stats against breaking balls. In nearly the same amount of breaking pitches seen the last two seasons (136 and 139) Davis has raised his average from .125 to .405! More absurd, in 2018 he did not have a single XBH against a breaking ball; he already has 7 this year. Specifically against sliders, Davis has an average exit velocity of 92.1 MPH and 7 knocks in only 15 Batted Ball Events. It seems like Davis cracked the code here and should keep mashing sliders and curveballs moving forward.

The fastball and fastball count are dying. It’s a fact of modern baseball. Identifying players who can touch up breaking balls, more so sliders, can help you to better project a player’s real-life and fantasy trajectory, especially in terms of the five hitters listed above.

Follow staff writer James Schiano on Twitter! @FreePeteAlonso

Follow us on Twitter! @Prospects365

Featured image courtesy of photographer Steve Mitchell and USA Today Sports