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Spitballing: Position changes June 3, 2011

Posted by tomflesher in Baseball.
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First thing’s first: this entry was prompted by Buster Posey and his horrific ankle injury, but it’s not just about him. The first time I started thinking about it seriously was last year, when the Mets’ Carlos Beltran was about to come off the DL and Angel Pagan‘s placement was in doubt. Either Gary, Keith, or Ron tripped my “Stuff Keith Hernandez Says” meter by saying that fans had suggested moving Pagan to second base to fill in for the ailing Luis Castillo, and commented that “You can’t just move a guy to second base.” Very true.

Similarly, it’s very hard to “just move a guy” to catcher, which is why a guy like Buster Posey is so valuable. In the National League, the median OPS+ for players with at least 100 plate appearances and who played more than half their games at catcher was 91. Posey’s OPS+ was 129 – that’s over 40% better. If instead you look at first basemen with at least 100 plate appearances, the median OPS+ is 107. All of a sudden, Posey’s offensive value-added drops to about 20% above average, and that’s before accounting for regression to the mean. Moving him to third base instead mitigates the damage and takes full advantage of his arm, but he’s suddenly a much less special player when he’s on the hot corner instead of behind the plate.

It’s also maddening to hear about efforts to move Derek Jeter to center field. Even though he’s on the downswing, he’s hit well above average every year from 1996 through 2009. Even last year, his 91 OPS+ was acceptable, especially considering his popularity. Granted, he costs his team runs on defense (he’s rarely had a positive defensive Wins Above Replacement), but his offensive contribution more than makes up for it. He’s 6’3″, making him more than big enough to move to first base, and first base doesn’t require him to have the range that center field would. After Jorge Posada hangs it up, splitting  the duties at first base and DH between Jeter and Alex Rodriguez will start to make more sense, and using homegrown prospects to take over at shortstop and third base ensures continuing fan loyalty.

Finally, I’d be remiss if I didn’t mention future Dodgers closer Kenley Jansen. Although his 2.000 OPS last year grossly overstated his batting ability (only two plate appearances, compared with a lifetime .229 batting average in the minors), Jansen is a success story in his move from catcher to fireballing reliever. That was an excellent move by the Dodgers system – they took Jansen’s innate ability (his cannon-like arm) and moved him to a position where his contribution would be optimized. Whether or not Jansen turns out to be a future dominant closer, he’s probably gotten more playing time as a reliever than he ever would have as a catcher, and he’s generated more value for the Dodgers.

Basically, player moves are difficult. It’s important to try to optimize a player’s contribution, and that needs to take into account his defensive talents instead of merely trying to find a place for him to play. I can only hope Buster Posey’s recuperation goes smoothly and there’s a value-maximizing slot for him with the Giants.


Back when it was hard to hit 55… July 8, 2010

Posted by tomflesher in Baseball, Economics.
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Last night was one of those classic Keith Hernandez moments where he started talking and then stopped abruptly, which I always like to assume is because the guys in the truck are telling him to shut the hell up. He was talking about Willie Mays for some reason, and said that Mays hit 55 home runs “back when it was hard to hit 55.” Keith coyly said that, while it was easy for a while, it was “getting hard again,” at which point he abruptly stopped talking.

Keith’s unusual candor about drug use and Mays’ career best of 52 home runs aside, this pinged my “Stuff Keith Hernandez Says” meter. After accounting for any time trend and other factors that might explain home run hitting, is there an upward trend? If so, is there a pattern to the remaining home runs?

The first step is to examine the data to see if there appears to be any trend. Just looking at it, there appears to be a messy U shape with a minimum around t=20, which indicates a quadratic trend. That means I want to include a term for time and a term for time squared.

Using the per-game averages for home runs from 1955 to 2009, I detrended the data using t=1 in 1955. I also had to correct for the effect of the designated hitter. That gives us an equation of the form

\hat{HR} = \hat{\beta_{0}} + \hat{\beta_{1}}t + \hat{\beta_{2}} t^{2} + \hat{\beta_{3}} DH

The results:

Estimate Std. Error t-value p-value Signif
B0 0.957 0.0328 29.189 0.0001 0.9999
t -0.0188 0.0028 -6.738 0.0001 0.9999
tsq 0.0004 0.00005 8.599 0.0001 0.9999
DH 0.0911 0.0246 3.706 0.0003 0.9997

We can see that there’s an upward quadratic trend in predicted home runs that together with the DH rule account for about 56% of the variation in the number of home runs per game in a season (R^2 = .5618). The Breusch-Pagan test has a p-value of .1610, indicating a possibility of mild homoskedasticity but nothing we should get concerned about.

Then, I needed to look at the difference between the predicted number of home runs per game and the actual number of home runs per game, which is accessible by subtracting

Residual = HR - \hat{HR}

This represents the “abnormal” number of home runs per year. The question then becomes, “Is there a pattern to the number of abnormal home runs?”  There are two ways to answer this. The first way is to look at the abnormal home runs. Up until about t=40 (the mid-1990s), the abnormal home runs are pretty much scattershot above and below 0. However, at t=40, the residual jumps up for both leagues and then begins a downward trend. It’s not clear what the cause of this is, but the knee-jerk reaction is that there might be a drug use effect. On the other hand, there are a couple of other explanations.

The most obvious is a boring old expansion effect. In 1993, the National League added two teams (the Marlins and the Rockies), and in 1998 each league added a team (the AL’s Rays and the NL’s Diamondbacks). Talent pool dilution has shown up in our discussion of hit batsmen, and I believe that it can be a real effect. It would be mitigated over time, however, by the establishment and development of farm systems, in particular strong systems like the one that’s producing good, cheap talent for the Rays.

Welcome to the Majors, Jay June 22, 2010

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Jay Sborz had a rough debut in relief of Justin Verlander during tonight’s Tigers at Mets game when there was a rain delay in the top of the 3rd. He faced seven batters in two-thirds of an inning, plunking the first two – Rod Barajas and Jeff Francoeur – and giving up hits to the last three. As Sborz, who was obviously struggling with nerves, tried to pitch his way out of the inning, Mets commentator Gary Cohen was mocking him mercilessly. “That’s got to be some kind of record,” for one.

Though Gary said it, that pinged my “Stuff Keith Hernandez Says” meter, and I trotted off to Baseball-Reference.com to look it up. Since 1973, six other pitchers who debuted in relief have two hit batsman. Were any of them as bad as Sborz?

We don’t have to go back too far to find someone who was. In 2002, Justin Miller of the Blue Jays made his debut against the Devil Rays and hit Chris Gomez, then Jason Tyner. Miller deserves special recognition – after that beautiful start, he held on to pitch 2 2/3 and got the win!

Honorable mention goes to Mitch Stetter of the Brewers. In a 2007 game against the Pirates, Stetter debuted in the last inning of a 12-2 blowout. He was on the winning side, though it ended up 12-3. Stetter hit Jack Wilson. He threw a wild pitch in the process of walking Nyjer Morgan, then iced the cake by plunking Nate McLouth. That was followed up with a groundout that scored Wilson and a merciful game-ending double play.

Trends in DH use June 11, 2010

Posted by tomflesher in Baseball, Economics.
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Last night, Keith Hernandez was talking about how the Mets are scheduled to play in American League parks starting, well, today. He pointed out that the Mets will be in a bit of a pickle because they aren’t built, as AL teams are, to carry one big hitter to be the full-time DH. Instead, an NL team will be forced to spread the wealth among lighter hitters who are carried for their defensive acumen as well as their offensive prowess. Keith then corrected himself and said that AL managers are using the DH differently – to rest individual players instead of having an everyday DH.

That pinged my “Stuff Keith Hernandez says” meter, and so I decided to crunch some numbers and see if that’s true. I interpreted Keith’s statement as implying that the number of designated hitters should be increasing, since managers are moving away from an everyday DH and toward spreading the DH assignments around a bit more. The crunching also needs to account for interleague play, which should obviously increase the number of DHes. So, after controlling for interleague play, does DH use show an increasing trend with time?