John Mayberry Jr’s Strikeout Rate

John Mayberry started the season in AAA for the Phillies and eventually got the call to the majors. He has been a pleasant surprise by hitting 15 home runs in only 275 PA. He had shown power in the past, but a large K% was limiting his HR and AVG production.

In 50 plate appearances with the Phillies in 2009 and 2010, he hit fly balls 43% of the time. Of these flyballs, 30% left the stadium for a home run. This season’s numbers are similar with a 39% FB% and a 19% HR/FB%. His ability to hit home runs has not changed. He is good at it.

The problem for John was that he could not make contact with the ball. In all minor league levels, he struck out 22% of the time. It peaked in 2009 when it was at 26% in AAA. Since that point, he looks to have made an effort to bring the rate down. Here are his AAA and MLB K%’s from 2009 to 2011:

Year: AAA K%, MLB K%
2009: 26.3%, 38.3%
2010: 20.3%, 30.8%
2011: 18.9%, 18.5%

He has seen a steady improvement in his strikeouts. Using batted ball data, the change can be attributed to his contact % going from 68% and 55% in 2009 and 2010 to 77% in 2012.

Besides the increase in chances for home runs, he will also have a better chance of getting a regular hit. More balls in play will mean a better AVG.

The change from striking out around 25% of the time and 19% will be significant. Using 20% HR/FB%, 40% FB%, 7% BB% and 0.290 BABIP as constants, here are the HR and AVG values by changing the K% from 25% to 19%:

25% K%: 0.253 AVG, 33 HR
19% K%: 0.276 AVG, 36 HR

The increase in home runs is only 3, but his AVG improves by about 25 points. A 0.253 AVG is not Adam Dunn horrible, but it will be a drag on a fantasy team. The increase in AVG to the 0.276 will be closer to the average value (depending on league size). The extra home runs are just icing on the cake.

For John to be valuable next season, he will need to continue keeping his K% under 20%. If he is able to do that, his AVG will be higher and not be as much of a drain.

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Jeff writes for FanGraphs, The Hardball Times and Royals Review, as well as his own website, Baseball Heat Maps with his brother Darrell. In tandem with Bill Petti, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Twitter @jeffwzimmerman.

8 Responses to “John Mayberry Jr’s Strikeout Rate”

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  1. Mike says:

    Don’t forget though that the Phillies have Victorino under contract, Pence arbitration eligible and Domonic Brown waiting to assert himself in left field.

    While his progression has been encouraging, Mayberry Jr. isn’t guaranteed to be more than a fourth outfielder in 2012.

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    • Brad Johnson says:

      Along a similar vein, I think it’s probably foolish to project full playing time for Mayberry Jr. at this point. Take a look back at how players like Werth and Utley were handled under Charlie Manuel. My guess is that Mayberry’s performance this year earned him a shot at 250-450 PA next season depending on a number of variables. If he then continues to show this level of talent, he’ll get wider consideration for a full time gig in 2013.

      Likewise, at this point, I wouldn’t pencil Brown in for more than 250 PA, and that’s only if he has a very strong spring. I’m expecting a LH free agent signee to split time with Mayberry.

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  2. novaether says:

    I’m expecting a RH/LH platoon of Brown and Mayberry in LF unless there’s an injury or one of them really asserts himself as the better player.

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  3. nik says:

    JMJ has probably been the most pleasant surprise for the Phils this year.

    Awesome trade for the Phillies to get him for another 1st round under-achiever Greg Golson.

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  4. Roger Goodell says:

    After being sent down, Dom Brown was nonexistent. He will start in AAA until he shows he can actually succeed there. Mayberry changed his whole stance and approach, mostly thanks to Ryne Sanberg, and hasn’t looked back. The chances of him not being the starting LF next year a very slim. Especially if he goes off in the playoffs, which I totally expect him to. Dudes a beast. Btw, platoon would be pretty stupid.

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  5. Nate says:

    His decreased K% can be attributed to his amount of at bats against LHP. 110 of his 250 AB (or 44%) were against LHP, much higher than normal Right Handed Batters get due to his platoon split. He also hit .309/.356/.600 vs LHP while hitting .250/.325/.471 vs RHP. In a full-time role, I would expect his K% to increase again with added AB’s vs RHP.

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    • Nathaniel Stoltz says:

      Well, if those AVGs are for real (it’s AVG, so it’s certainly possible they aren’t), then he’d still project to hit around .265, which is above the .253 the article states he’d have with his old K%.

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    • joshcohen says:


      the percent of ABs he’s faced lefties hasn’t really changed since 09. over his career, he;s always taken about 40% of his ML ABs against lefties. thus, his decreased K rate isn’t wholly a product of this split, or it would have been seen in prior years.

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