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What if Francisco Mejía’s plate discipline is a feature and not a bug?

His swing decisions may be a byproduct of a greater plan

MLB: Toronto Blue Jays at Tampa Bay Rays Nathan Ray Seebeck-USA TODAY Sports

What stands out to you when you watch this video?

Hopefully, you noticed that Rays catcher Francisco Mejía struck out swinging on a pitch that missed the zone so bad that it hit him. Obviously not an ideal outcome for any batter.

What do you notice when you watch this next video?

The pitch missed its spot so badly that it was never going to be a strike, but Mejía didn’t care - he slapped it down the LF line for a double.

Try not to be too surprised when you read this: over the past two seasons, nobody in baseball with at least 100 plate appearances has swung at pitches out of the zone at a higher rate than Francisco Mejía. It could be argued that he is the least disciplined hitter in baseball.

I’ve always thought that Mejía was just a second-rate, swing-happy switch hitter, slated to be a backup for his career. His defense isn’t great (although he does have an absolute cannon of an arm and that might raise his defensive value with the new rule changes), and his bat is average at best with a career 96 wRC+ since joining the Rays prior to the 2021 season. His offensive production is limited by his plate discipline... or is it?

The Rays consistently find themselves pushing the boundaries of new and exciting innovation in every facet of the game. What if we entertain the possibility that this is exactly what they’re doing with Mejía? What if his approach at the plate is a feature and not a bug?

Why would the Rays want Mejía to swing at everything?

I believe he has the skills to be a guy that can sustain a high BABIP, and the Rays might be trying to harness those skills in order to maximize his production. The more I read, learn, and grow, the more I’ve come to understand that being able to carry a higher-than-average BABIP is a real skill that some batters are good at.

What have his BABIP numbers been like so far in his career?

Mejía might not look like he could pull this off at first glance; his BABIP in the majors has been just .285 for his career and .292 during his time with the Rays. The league average BABIP in each season since 2000 has ranged from .303 to .290 (and trending down over the past three years, but maybe the shift-ban changes that), so it’s clear the Mejía has yet to show the ability to post above BABIPs consistently. However, I will note that he does have a career .330 BABIP in the minor leagues dating back to 2013 and the minor league average BABIP among qualified hitters since then is .310. But don’t worry, I’ll dive much deeper into this topic than a simple one-to-one comparison involving Mejía’s major league and minor league BABIP.

How to BABIP

To begin, it’s important to acknowledge the idea that having a high BABIP isn’t necessarily always about being “lucky.” It’s a real skill, and baseball guru Tieran Alexander does a great job explaining that in this article.

There are a number of factors that influence BABIP, but three he lays out in his article are hard hit%, sweet spot%, and pop-up%. How does Mejía stack up on the three “pillars of BABIP”?

Pillar one: hard hit%

Hard hit% is the percentage of batted balls greater than or equal to 95mph. Mejía had a hard hit% of 28% (not far off from his career average of 28.5%) last season which places him in the 5th percentile. So it seems like we’ve already run into a problem, right? Not exactly. Despite a low hard hit%, Mejía still maintains very consistent exit velocities. His average exit velocity on non-hard hit balls (anything less than 95mph) last season was 81.9mph - good enough to put him in the 83rd percentile. He has a significantly higher floor in this measurement compared to the rest of the league.

Mejía doesn’t consistently hit the ball hard, but he does hit the ball mediumly(?) hard with great consistency. For what it’s worth, known BABIP king Luis Arraez has similar hard hit% and exit velocities to Mejía, but was the best in MLB in average exit velocity on sub 95mph batted balls. For more info on this interesting wrinkle surrounding exit velocities, check out this really great article.

Pillar two: sweet spot%

Sweet spot% is simply the percentage of batted balls with a launch angle between 8 and 32 degrees. Mejía posted a career high 39.1% sweet spot% last season, landing him in the 93rd percentile. So Mejía hits the ball with consistent exit velocities - but not too hard - and his batted balls are consistently within an optimal range more than 93% of other batters in the league; so why was his BABIP just .292 last season?

Pillar three: pop-up%

The third pillar of BABIP - pop-up% - was easily Mejía’s biggest weakness. While he did manage a career low 9.2% (placing him in just the 58th percentile), it wasn’t good enough for him to be a BABIP guy with his already low hard hit%. The silver lining here is the rolling 50 game average on his infield fly ball rate (see below). Take a wild guess as to when he was acquired by the Rays... Answer: right before the start of the 2021 season.


Where do we go from here?

This is where his absurdly high swing rates come into play; over the past two seasons, only 5 players in MLB have a higher swing rate than Mejía (min 500 PA) at 58.3%. Despite this high rate, Mejía doesn’t make a ton of contact. Both his contact rate (78.9%) and zone contact rates (86.6%) are relatively low compared to other BABIP guys - ranking in just the 63rd and 54th percentiles respectively.

This makes it seem like his BABIP journey could fall short, but I don’t think that’s the case; He’s sacrificing some swing and miss in order to maintain his batted ball quality (for him, batted ball quality = consistent launch angles and exit velocities). He could probably make more contact if he were to slow his bat down a bit, but that would mean a drop off in his intentional batted ball quality. This leads me to believe his high swing rates are a feature, not a bug. It’s good for him to swing hard and often because his quality of contact is in the optimal range for him to be a BABIP merchant.

Furthermore, Mejía has the plus bat and barrel control needed to pull off this transition to BABIP guy. His hit tool received 60 grades as a prospect, and it’s no accident he put together a 50(!) game hit streak in the minor leagues.

I mentioned before that Mejía has consistent, although relatively low exit velocities. It’s also worth noting that he has a relatively consistent launch angle. The standard deviation on his launch angle in 2022 was just 28.1 degrees, placing him in the 60th percentile. The lower the standard deviation in launch angle, the more consistent the launch angles are on batted balls. Mejía does this at an above average, but not elite rate. However, he is improving:

Baseball savant
Baseball savant

We can see his launch angles becoming more consistent year over year in addition to more consistent exit velocities at the optimal launch angles. So the good-but-not-great 60th percentile mentioned above is only going to get better. More consistent launch angles with more consistent exit velocities at those launch angles should yield an improving BABIP. Spoiler alert: it has already started.


Expectations for 2023

I expect Mejía to continue to improve his batted ball consistency while he stays on track to lower his pop-up%. I also expect Mejía to benefit from the shift ban to an extent when he’s batting from the left side; his BA as a LHB was 84 points lower than his xBA on pulled balls with a launch angle between -15 and 15 degrees.

Speaking of pulling the ball, the league BABIP last year on line drives was .618. Pulled line drives had a BABIP of .663. Can you guess who had the 9th highest pulled LD% on batted balls in MLB in 2022? If you said Francisco Mejía, you’d be correct. His 13.3% pulled LD% put him in the 97th percentile among all batters with at least 200 batted balls. This high rate isn’t a fluke as his LD% has been improving since joining the Rays:


Here’s Mejía’s formula for success through BABIPing:

Continue improving launch angle and exit velo consistency + continue pulling the ball + continue limiting popups + benefit from the shift as a LHB

What you can expect from Mejía in 2023 is to continue to swing away at anything and everything.

Is it sustainable? Maybe.

Is it a cool experiment for the Rays to run with a unique hitter? Yes.

Is it fun? Absolutely.