Examining ISO Changes From 2009 to 2010

Every year there are several players that surprise and disappoint with their power numbers. Today, I am going to look at the players (min of 400 PA) that increased or decreased their ISO the most from 2009 to 2010. Besides just looking at the numbers, I have gone ahead and run a LOESS regression against some player’s line drive and fly ball data to help find the cause of the change in power. First of all, here are the leaders and laggards:

No real surprise with Jose Bautista leading the list. There are a couple of cases where a player went from a from one team to another and their numbers changed significantly (Jason Bay going from Boston to the New York Mets).

Next I will look to see if any of these changes were due to changes in the player’s talent or changes in their environment. To do this analysis, I am going to look at changes in the the batted ball distance and direction of fly balls (including home runs) and line drives from one year to the next. Because there are large changes from one batted ball to the next, I have plotted a LOESS curve against the data to look for small changes in the player’s hitting pattern. The distance is important to determine the power behind each hit. Looking at the angle determines if the player is able to turn on a pitch and drive it into one of the outfield corners where the fences are shorter. Now here are graphs of league’s top and bottom two players who changed their ISO from 2009 to 2010.

The data is from MLB Gameday data. The negative value for batted ball angle shows balls hit to left field and a positive value is for right field. The distance is in approximate feet. This data is not in any means perfect or close to it, but it is currently the best freely available data.

Jose Bautista (+0.184) – 2009 and 2010 with Toronto

Jose began to turn on the ball with more power at the end of 2009 and he continued that trend into 2010. His average distance hit per ball went up almost 70 feet from the beginning of 2009. To go along with a 30 degree change in angle, he became 2010’s top home run hitter. Seeing if these trends continue in 2011 will be interesting.

Adrian Beltre (+0.119) – 2009 with Seattle (Park Factor = 97), 2010 with Boston (Park Factor = 107)

Adrian’s 2009 and 2010 graphs are almost identical even though his ISO increased over one hundred points. Hitters love Fenway Park.

Jason Bay (-0.125) – 2009 with Boston (Park Factor = 107), 2010 with New York Mets (Park Factor = 95)

Jason’s distance graph is similar, but he did not turn on the ball as much in 2010. His home run numbers may go back up a little if he is able to pull the ball more. Hitters though hate leaving Fenway Park.

Ben Zobrist (-0.131) – 2009 and 2010 with Tampa Bay

Being a switch hitter, it is tough to say if the change in angle made much of a difference in Ben’s loss of power. He did drop his average distance hit by 30 feet, which explains some of his drop in ISO.

I am just beginning to scratch the surface with the batted ball data so let me know if you have any questions or if there is any other players you would like looked at (I can only go back to 2007 currently, but hope to have 2005 and 2006 data soon).

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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.

27 Responses to “Examining ISO Changes From 2009 to 2010”

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  1. exxrox says:

    As a Jays fan, I love me some Jose Bautista. The changes he was able to make from Sept 2009 onward are just incredible. He shortened his loadup for his swing and turned it into one of the quickest in baseball…at times it looked as violent as Gary Sheffield in his prime.

    This is going to derail the comments off-topic, but here’s an interview that I am sure not many people have seen:


    …you may continue with the ISO comments

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  2. Jack Nugent says:

    I’d love to see Derrek Lee’s chart. Given that he’s a free agent right now it seems like he’s worth a look.

    Gotta believe D-Lee is pissed he barely reached Type A status. I bet this has a big impact on his value.

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    • harpago17 says:

      I really doubt that Derrek Lee is that upset about reaching Type A status, since I think that the Braves will be too gunshy to offer him arbitration due to the risk of him accepting. If anyone is pissed it’s probably Frank Wren and the Braves front office, since the likelyhood of Lee accepting arb is much higher as a Type A than a Type B.

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      • hk says:

        Whether Lee is Type A or Type B should be irrelevant. Unless Lee agreed to decline arbitration as part of being traded to Atlanta at the deadline, there should be now way that Wren will offer arbitration (regardless of potential compensation) with Lee coming off a 2.1 WAR age 35 season where he made $13.25M.

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  3. Red Sox Talk says:

    I like your train of thought on Fenway, but the problem is that Adrian Beltre’s 2009 was an injury year for him. While many of his batted balls fit his usual pattern, it’s hard to say it was a park effect when his ISOs were .197, .207 and .191 the three previous years in Safeco. Despite a relatively normal BB profile in 2009, his HR/FB was a mere 5.9% last season, which is way below his career 13.1%. And this year he hit some more flyballs than usual too. Fenway is actually not a HR-generating park overall (I believe it helps righties slightly, but lefties really suffer). Doubles, yes.

    Jason Bay’s 2010 is also an injury season, so it might be a mistake to point to the park as the only reason for his power drop. He hit an unusual number of fly balls in 2009 (49.1% compared to 44.5% career), with 19.7% of them going for homers, compared to 15.8% lifetime.

    What it looks like is that right-handed hitters are lofting the ball more in an effort to take advantage of the short fly ball HRs over the Monster.

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    • quint says:

      I am not a fan of the train of thought on Fenway since Beltre hit better away from it, so unless he was taking the Wall on road games…

      What the article should have said was that the AL East parks are hitter friendly by and large, and the AL West not so much.

      But its Beltre, so it was 96% free agent year.

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      • Terminator X says:

        Uh… you realize they were BOTH free agent years, right?

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      • quint says:

        Terminator – not what I was commenting on. Red Sox Talk said he liked the articles train of throught on Fenway and Beltre – and I said I didn’t since Beltre hit better on the road.

        I was commenting on my opinion was that Beltre didn’t have big numbers because of Fenway, but because it was his free agent year (historical) and because the AL East ballparks by and large (and not just Fenway) are better hitting parks than those in the AL West (where he just came from).

        In no way shape or form did I comment on Jason Bay.

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      • chulton says:

        Allow me to respond for Terminator.

        Both years in question for Beltre were free agent years so you’re reasoning that his stats increase is due to him being in a contract year can be completely discounted.

        I do, however, think that there is some validity in thinking that Fenway was not solely responsible for his increase in ISO. Afterall, his numbers were just as good if not better away from Fenway.

        Jason Bay is a whole different issue, as I believe some of his ISO problems were ball park related. Jason Bay is a fly ball hitter and as previously stated he hit 49.1% of his balls in the air in 2009. In addition to that, his batted ball profile shows that he had a knack for shooting those fly balls towards the Monster.

        As someone who has watched the Sox religiously for the last 10 years or so, I can easily say that I never saw someone hit more balls that barely scraped the wall or snuck over it for a home run. These are balls that likely would have been outs in any other ball park. So when you take fly ball hitter and put him in a home ball park with a huge outfield, it comes as no surprise that his ISO dropped.

        I don’t think this accounts for his entire drop in ISO, but it is part of the explanation, along with injury, for why Jason Bay posted a career high ISO in 2009 and a career low ISO in 2010.

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    • philosofool says:

      Seattle killed Beltre. Look at his home-road splits from his Mariner years. It wasn’t being in Fenway but away from Safeco that made the difference.

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      • joser says:

        Actually, I think Beltre did take the monster with him on the road in 2010 — in his head, in exactly the same way he took Safeco’s cavernous LF with him on the road during his Seattle years.

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  4. t ball says:

    I’m hoping that Kinsler’s spring ankle injury was to blame for his drop in ISO. His rate climbed month to month over the season, but still ended well below his 2009 mark.

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  5. Lee Panas says:

    Great stuff Jeff. The Bautista angle start is especially striking. It’s good to see that his power increase might have something real behind it.

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  6. Matt says:

    It sure does….real HGH.

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  7. Matt says:

    Let’s see.

    His ISO spiked 184 points in his age 29 season, an age where decline typically starts to set in. Keep in mind an ISO of 184 is solid in and of itself; but Bautista’s increased by that amount to a Pujolsesque 357.

    Now the “swing angle” take is a cute cover for pundits that want to believe this is 100 percent legit. No doubt he has changed his approach, including the angle, but he most certainly is on PEDs as well.

    Previously mediocre hitters don’t become mega-mashers at age 29 without help. And his homerun distance increased by what? 70 feet? C’mon.

    MLB can’t test for HGH yet, and the players know that. I am simply connecting the dots.

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    • Lee Panas says:

      So, why is Bautista the only one with such a big increase then? Aren’t other players taking HGH too?

      I don’t doubt that a lot of players are using HGH. I just don’t like it that any time any player has a big year now, he gets accused of using PEDs.

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      • Matt says:

        Hey – I agree. It is tiresome, but it’s the bed baseball has made.

        For me, with Bautista, it’s the age of the power spike and the magnitude of the spike that make me suspicious. Obviously, no one but Bautista knows the truth, I just think he’s on something.

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  8. Matt says:

    Pardon me, 70 foot increase per hit ball, not homerun.

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  9. Scout Finch says:

    So what’s in the drinking water in Toronto?

    Vernon Wells in #3 on the list. Alex Gonzalez slugged .497 (career high pace) w/ Toronto and .386 w/ Atlanta. John Buck just netted a 3/18 contract after popping 20 HRs.


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    • Someanalyst says:

      All that will change somewhat with Cito’s departure. It is funny to me that people often seem to act as if players played independently of their coache’s instructions (you know, the guys that determine their playing time…).

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  10. Jeremy says:

    I would like to see which players had their distance and angles change for better or worse toward the end of this season. It would be interesting to see if it carries over into next season. This seems like it could possibly be a valuable tool in predicting spikes in home run production and regression. The more of these graphs the better!

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  13. nolan says:

    I think injuries can explain Zobrist. He was having back problems for a good chunk of the season. That said his talent level is probably somewhere between 2009 and 2010.

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