The historic rookie season of Pete Alonso almost seemed to have no limits. The decision to bring Alonso to Queens after Spring Training was perhaps the best single move made by the front office this past season. Let’s see, he broke the Mets rookie and single-season home run records, was selected to the All Star Game where he won the home run derby, and claimed the title of MLB record holder for home runs in a rookie season – all of which led to a pile of post-season hardware, the most important being named Rookie of the Year. Alonso’s success came from phenomenal long-ball power, so I wanted to look into the 53 home runs and see what details, if any, could be learned about the slugger beyond face value. Are there obvious location strengths or holes in pitch location? Righty versus lefty pitching? Time of year? Let’s find out.

The first part of this appraisal was to re-watch (at least five times) every full at bat when a homer occurred and chart the pitch sequence as best as possible given limitations of an off-center outfield camera. I used the SNY feed for every home run except where one did not exist. The data were visually plotted in the standard 3×3 location matrix, but then reduced to five locations instead of nine: most fans can see the middle-middle part of the zone pretty well, so I used that field and from there inner-and-outer zones and upper-and-lower zones providing 4 quadrants around “center cut” locations. I recorded the pitch type (fastball or off speed), pitching hand (L/R), and inning. Home runs were charted individually and then grouped by month, which provides enough data for each segment, and still gives six looks across a season.

Most players have a sweet spot or pitch preference or some combination where they have a lot of comfort and so are proficient at hammering the ball, a trait that should be reasonably projected for Alonso. Before getting to the pitch location details, some basic things are worth noting. Thirty-nine of the home runs came against right-handed pitchers, leaving 14 coming against lefty pitching. Rather than a preference to crush RHP, this more likely represents facing more righties than anything else. As far as pitch selection goes, 60 % came from fast balls and 40 % came off of off-speed pitches. Alonso does not seem to care about who he faces or what pitch is coming at him. Talk about an offensive threat.

Assessing the pitch locations as a whole, that is looking at all 53 home runs in one plot showing middle-middle, upper-outer, upper-inner, lower-outer, and lower-inner reveals that not only does Alonso not show a preference for pitch type or delivery hand, he is phenomenal at covering the plate. To my surprise, Alonso homered in the middle-middle (30 %), upper-outer (30 %), and lower-outer (26 %) with pretty much equal devastation, with the remainder coming from the inner half. In all 53 at bats, the overall pitching strategy was to pitch Alonso away, and more down than up.

What approaches were pitchers taking, and is there anything opposing arms might use to get more success in 2020? One thing in the data is clear, Alonso crushed 32 homers (60%) seeing fewer than four pitches, so not much of an approach exists for those. Attacking a batter up with speed is certainly a modern approach to exposing batters prone to eye-level changes, but Alonso is a monster up in the zone, with the majority of fastball homers coming middle and up. Breaking pitches low in the zone and away is another common pitching tactic, although Alonso hit 55% of his off-speed pitches low and away. Alonso’s capacity to cover everything on the outer half, with fastballs or off-speed pitches only adds to his advanced hitting skills.

Given the amazingly comprehensive hitting approach Alonso shows in the home-run-hitting at bats, it seemed reasonable to appraise his consistency across the season and to explore if the home runs came in certain innings. In April, Alonso capitalized on apparently weaker relief pitchers to start his epic run by hitting quite a few late in games, but that was an anomaly. By inning, he hit the most in the first, the fewest in the second and third (as expected giving batting order), then hit them pretty evenly in the fourth through ninth. As far as the season goes, Alonso averaged 8.8 (+/- 1.6) home runs per month, with July really his only departure from the standard deviation; that is not a surprise given the All Star Break and the Home Run Derby blow out.

The data from this season demonstrate that Alonso is much more than a guy who runs mistake pitches out of the park. In virtually all respects of his hitting approach, he could easily be labeled “Mr. Consistency,” not prone to wild streaks like we see with Michael Conforto. Even with the strikeouts, Alonso has a solid eye for the whole strike zone, and capacity to put damage on a ball anywhere in the zone. Sure he hits a lot of home runs, but what the data show is a complete offensive threat that Mets fans should enjoy for a good long time.

Looking to pitchers for next season, it would be hard to offer a plan for succeeding against Alonso. He hit the fewest number of home runs on the inner half, so maybe that’s a plan, but any mistake will have a certain outcome for sure. That Alonso is hunting for good pitches in any count and commonly capitalizes early on, one approach may be to offer him more pitches with the hope of expanding his zone significantly, but refusing to fall behind and serve up the middle-middle pitch for which he is waiting.

1. Pete Alonso was successful at hitting home runs against left- or right-handed pitching, fastballs or off speed pitches.
2. Alonso covered the entire outer part of the strike zone equally well, hitting home runs up and down in the zone. His home run tallies are about equal in each month of the season and in virtually all innings.
3. All the data from the home run at bats in 2019 demonstrate Alonso as a consistent hitter with a strong sense of the strike zone.

5 comments on “A deep dive into the 2019 HR barrage of Pete Alonso

  • Brian Joura

    Great work Chris!

    Everyone needs to click through all 11 slides in the embedded PowerPoint. Based on Slide #2, I’d expect pitchers to attack him inside more often in 2020.

  • Bob P

    This is a really cool analysis. Nice job Chris. I’m surprised at how few inner half pitches Alonso hit out this year. Like Brian said, I would expect to see him get pounded inside even more last year. If they do that, who knows how many HBPs he will have!

  • Terry

    This is awesome! Hope you don’t mind if I include video of all of his HR

    • Howard

      Terry, Thanks so much for posting this awesome video

  • TexasGusCC

    Great job Chris, as this is a ton of work. I couldn’t help but notice as the homerun totals were rising, the pitches still stayed away. Wright had that opposite field power, as did Piazza, but Citifield is a pitcher’s park! Too, much of his damage was on fastballs, which we will see a change in pitching patterns next year.

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