Where Did Yonder Alonso’s Fly Balls Go?

Yonder Alonso is now a Mariner, and for a player that just added a ton of fly balls to his repertoire (and the power that comes with it), hopefully that change of scenery will be a salve. Because Alonso has lost those fly balls momentarily. He thinks he knows why.

It’s been a big and worrisome drop in fly balls in July and August, especially given that his career fly ball rate is 34%.

Alonso’s not worried. “Just a little bit of timing issue right now,” he said last week. “Pitches I was hitting right I’m just missing — Late, early, just missed the ball.” Before he trailed off, he added something interesting: “I’ve been hitting a lot more foul balls.”

Turns out, that’s a big part of the story about where the fly balls went. Take a look at his foul percentage next to his fly ball percentage, and July stands out.

Yonder Alonso’s Flies and Fouls by Month
Month Fly Ball % Foul%
April 32.9% 12.8%
May 35.6% 16.5%
June 29.4% 16.7%
July 19.5% 19.0%
August 22.2% 16.7%
Fly balls converted to fly balls divided by plates appearance to fit the foul ball %

It’s clear from the updated fly ball numbers — here shown by plate appearance vs balls in play — that the foul ball thing doesn’t explain it all. But the foul balls could still be an indicator of the underlying problem: timing.

Alonso says that he has a plan to fix the issue: “I’m working, doing the net drill. I feel like it’s about to come back.”

The net drill, most famously part of Robinson Cano’s arsenal, helps players avoid casting, or drifting over the plate, by putting a constraint on how far out they can swing. “Stay behind the ball, not diving at it,” Alonso added. “Thats the reason I was rolling over, I haven’t done that in a while.” Here’s Sean Casey breaking down the benefits of using the net:

The drill is not without its detractors, but hitting coach Ryan Parker pointed out the mindset that can make that practice work for a power hitter. “I like it as long as hitter is driving the ball to big part of field and not just filleting balls to the opposite field,” he said. With Alonso’s big adjustment coming largely from just this sort of adoption of a power-friendly mindset in the offseason, he might be the right player doing the right practice at the right time.

Hopefully with a little more work, Alonso can right the ship and help the Mariners reach the playoffs. The team has a 22% chance according to our playoff odds, and are currently behind the Royals and Rays for the second playoff spot. With their new first baseman, they’re in the middle of the pack on the depth charts at the position instead of being in the bottom third.

A little quirk of timing may help the player and the team, even if monthly splits haven’t been proven to be predictive across baseball. “My career says that I’m at my best in August and September,” pointed out Alonso. He’s been 12 percentage points better in the second half over his career, relative to league average.

“The swing’s still the same, I’m still doing the same thing,” Alonso said. “I feel good.”

[This post was updated to put the fly and foul ball numbers over the same denominator.]

With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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6 years ago

Just for everyone’s information, if you want to see all the comments, click to sort comments by “Newest” or “Most Voted”.

AJ pro-Preller
6 years ago
Reply to  LHPSU

I like the Mariners/Paxton if they make it to the one game playoff.

baltic wolfmember
6 years ago
Reply to  AJ pro-Preller

Everybody does! But what starters will the M’s trot out after that? Felix is hurt and not for the first time.

6 years ago
Reply to  AJ pro-Preller

Over Sox/Sale or Yankees/whichever starter + that bullpen? I’m certainly not betting on Seattle.

6 years ago
Reply to  CM52

They can’t play the Red Sox in the Wild Card play-in because the Red Sox are winning the division… they could play the Yankees though.