What’s Fueling Adam Dunn’s Resurgence?

After suffering through an abysmal 2011 season, White Sox designated hitter Adam Dunn is off to a fantastic start this year.

Last season, the 31-year-old Dunn put up a career-low .266 weighted on-base average (wOBA), or 59 wRC+, in nearly 500 plate appearances. His on-base percentage — which normally was a strength for the slugger — was .292, or 62 points below his previous career low when he was 23. Most disturbing was the sudden disappearance of his power. Dunn has always been a high-strikeout, high-walk, high-slugging player. But last year, Dunn posted an isolated power of only .118. To put that into perspective, consider this: Dunn’s ISO was only two points higher than Nyjer Morgan’s (.116). Dunn also saw his HR/FB ratio drop to 9.6% in a hitter- and home-run-friendly park. His previous career-low was 17.8%, all the way back in 2002.

But now? Well, we’re seeing the old Adam Dunn. Through May 7, he has managed a .394 wOBA, which is fueled by a .364 OBP, .321 ISO and a 28.1% HR/FB. And both the ISO and HR/FB numbers are better than his career highs. The obvious question is whether these numbers are sustainable. Given how quickly outcomes like BB% and HR/FB stabilize, there’s a good chance that Dunn’s end-of-season numbers could be similar to what they are today. The question I have is what is Dunn doing differently? To get a better handle on this, I took a look at Dunn’s performance on specific pitches in different locations.

With a methodology that I’ve used previously, I compared Dunn’s 2011 and 2012 performance by calculating the wOBA per pitch in different locations using PitchFx data. The chart below compared Dunn’s overall performances for those two seasons:

Even without producing a chart that shows the wOBA/pitch differential in each quadrant, it’s obvious where the biggest change has occurred. Dunn is absolutely crushing balls down the middle of the plate. Remember, taking a strike is comparable to making an out when calculating wOBA in this way — and pitches down the middle are rarely called balls. So the positive run values that Dunn is creating in this zone is solely attributable to making pitcher’s pay for throwing pitches in the fat part of the zone.

Dunn isn’t seeing more pitches in this zone (actually .4% fewer than 2011), but he’s attacking these pitches at a higher rate. Last year, Dunn took more than 30% of  the pitches thrown down the middle. This year? He has dropped his take percentage by 10%.

Dunn also is making the most of fastballs he sees in this zone. In 2011, Dunn seemingly lost the ability to handle fastballs and posted a wOBA per fastball of .104. That’s compared to .152 so far in 2012. The biggest difference? Once again, it’s in the heart of the strike zone:

What accounts for the change? I’m not sure. Late last season, in an interview with David Laurila, Dunn suggested that his problems may have been due to adjusting to the new league:

“I’ve been using a lot more [scouting reports and data] because this is my first time in the American League. I have to rely on stuff like that. I didn’t much before, because I knew the pitchers. And if I didn’t know the pitcher, I kind of knew the team’s philosophy on how they wanted to pitch me. That made it a little easier.”

Being less sure of how pitchers will attack you can make batters more hesitant, leading to fewer swings and weaker contact.

Regardless of the reason, it’s clear that Dunn’s resurgence against the fastball has fueled his numbers early this year. Dunn has been more aggressive, which has led to an increase in his whiff and strikeout rates, but the net results have been numbers that reflect the hitter the White Sox thought they were getting when they signed him as a free agent.

In terms of the sustainability of these numbers, there’s one aspect that should give us pause: Dunn’s platoon splits. While he has improved versus his performance last year, Dunn is still below his career average against left-handed pitchers.

In 2011, Dunn’s OBP when facing left-handed pitchers was 108 points below his career average. His ISO (-.200) and wRC+ (-105) were also drastically lower. Early this year, Dunn has improved those numbers against lefties — but as the table below shows, his performance still significantly trails his career norm.

Season Split BB% K% OBP OPS ISO wRAA wOBA wRC+
Career-2011 vs L -3.50% -3.80% 0.108 0.465 0.200 37 0.165 105
Career-2012 vs L -1.90% -9.40% 0.080 0.344 0.144 27 0.123 75
2012-2011 vs L -1.60% 5.60% 0.028 0.121 0.056 10 0.042 30

So while there are reasons to believe Dunn has righted the ship, his performance against lefties leaves a pretty big question mark. If he doesn’t improve against southpaws — and his blistering performance against right handers  (.467 wOBA in 2012, .388 career) comes back to earth — Dunn’s regression later this season could be a harsh one.




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Bill works as a consultant by day. In his free time, he writes for The Hardball Times, speaks about baseball research and analytics, consults for a Major League Baseball team and appears on MLB Network's Clubhouse Confidential. Along with Jeff Zimmerman, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Tumblr or Twitter @BillPetti.

24 Responses to “What’s Fueling Adam Dunn’s Resurgence?”

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  1. Steve K says:

    His Platoon splits suck, but he only has 39 PA against lefties at this point which could be just bad luck. It might take the whole season before this bears out.

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  2. West says:

    He’s using a lighter bat this season after refusing to last season.

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  3. mcbrown says:

    So if we’re drawing conclusions about Dunn’s HR/FB rate based on his sample of 33 flyballs, is it safe to say we are ready to stick a fork in Albert Pujols once and for all? After all, he has an even larger sample of 36 flyballs! Pujols is done, it’s over – the Angels should just cut their losses, eat the rest of his contract and release him.

    (I jest, but you get my point. I’m glad to see Dunn looking more like himself, but let’s not get ahead of ourselves.)

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  4. jcxy says:

    Interesting charts. Would we expect that 2012 would resemble 2010 or is there something new (someone suggested a lighter bat–might help with plate coverage?)

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  5. nuflattop says:

    Let’s not forget, Dunn also had an in-season appendectomy last year.

    That’s gotta mess with a swing…

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  6. Choo says:

    The answer of course is chicken pot pie.

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  7. Ignorant Tool says:

    How many other proven stars have had one abysmal season only to bounce back the next year I wonder? Lance Berkman comes to mind… but I still think Dunn’s 2011 full-season slump is in a class of its own.

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    • Andre says:

      Agreed. Interesting question though. That White Sox center fielder who came from the Blue Jays, was sort of a star, and had a nice bounce back year (in 2011?) after an abysmal year (in 2010?). So there’s that too.

      As an Angels, here’s hoping Vernon Wells is the next Adam Dunn story.

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    • miffleball says:

      this was kinda my presumption…good player his whole career, has a bad year when he started the year hurt, on a new team, in a new league and now he’s back to his usual self.

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      • miffleball says:

        but where’s the discussion about bautista’s return to his old self? are we supposed to just not notice it after there were tons of articles extolling his virtues the last two years?

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    • vivaelpujols says:

      Berkman was still a well above average hitter in 2010.

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  8. Matty Brown says:

    Last season I spent $34 on Dunn in Ottoneu, this season I thought he’d be great value, I only paid $6 this year.

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  9. MikeS says:

    Interesting factoid. Adam Dunn has struck out in every game he has played this year. Even a game where he only had 1 AB as a PH, he struck out. I know he strikes out a lot, but even last year he had 22 games where he did not strike out.

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    • MikeS says:

      Just saw that with tonight’s K he has struck out in 36 straight going back to last year, one short of Bill Stoneman’s record set in 1972-72.

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    • macseries says:

      another interesting factoid: tonight’s game was the 99th “true result” game of his career.

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  10. Brian says:

    It’s because he’s not on my fantasy team this year. Also, just as a warning to everyone, I just traded for David Wright, so … now is probably a good time to let him go.

    On an actual baseball-related note, its truly an amazing resurgence. Last year’s malaise wasn’t luck-related, or injury-related … it was, “this guy just can’t hit a fastball anymore”-related, and he looked like toast. For him to return to his career norms like this is just remarkable.

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  11. Kyle says:

    Last year was just an aberration in the power department. I don’t know if it was the league change, his approach before the regular season or what.

    Yearly, he goes up and down vs. lefties(and it’s almost an anomaly.) He’s been all over the place. In 2005, he hit .198 against lefties but hit .270 against them in 06. His average dropped from the right side to almost .200. Then hit .195 against lefties in 2008 but managed to come back in 2009, and hit .268 vs. them. So… I have no idea what it means but it’s kind of odd and really can’t remember another hitter who’d have such unpredictable production at the plate against pitchers based on that.

    Barring injury, he’ll be good for 30 to 40 homeruns a year while striking out more and more… he also doesn’t play for Ozzie Guillen who called out Javier Vasquez right before they played the Twins for 3 games to get to the postseason saying, “”He hasn’t been,” Guillen said Sunday of Vazquez as a big-game pitcher, “That’s the bottom line.”

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  12. AJ says:

    The good thing about Dunn in daily fantasy leagues is that you can bench him whenever the White Sox face a lefty starter. I’ve done that all year and I’ve still gotten every single one of his 10 homers, and a .265 average (as opposed to his .242 overall). By balancing him out with a high average, speed guy (Gerardo Parra), I’ve managed to get 10 hr/20 rbi/.270./3 SB out of my utility spot in a 14 team league… which is basically Jay Bruce.

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  13. S. Urista says:

    I’m not necessarily all that worried about his numbers regressing – didn’t the club say he’d get a few more off days when the other team had a lefty on the mound?

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