Posted by: Peter | March 3, 2010

Expectations and uncertainty

I share the general consensus that the Twins had a very good winter. They basically did everything I could have asked for, short of picking up a third baseman. I’m excited about J.J. Hardy, Orlando Hudson is a solid addition, and Jim Thome is just the frosting on top.

It makes me a little nervous that, to a lot of people, the Twins are favorites in the AL Central now. After surprising everyone with last season’s ridiculous comeback, I’d hate to see them let everyone down this year, especially since it would bring on a cavalcade of idiotic stories about how they can’t stand playing outside or how they’re lost without the advantage of the Metrodome roof.

This got me thinking about the performances I’m expecting from various players this year, and what they mean for the team’s chances of either overachieving or disappointing. Now, it’s easy to find lots of projections for how different players will perform, and by combining those you can get an idea of the most likely win total for the Twins this year. What you don’t generally see, though, is much discussion of the uncertainty around these various projections. (PECOTA does some of this with their “Breakout rate” and “Collapse rate”, but you have to pay to look at those numbers.) Particularly on this year’s team, the level of uncertainty surrounding different players varies wildly. With some guys, we more or less know what to expect, for better or for worse. With other guys, almost anything could happen.

So with that in mind, I decided to to a quick-and-dirty little study of the probable starting lineup and pitching rotation. I wanted to know two things:

  1. Which players have more uncertainty surrounding their performance this year?
  2. Is the uncertainty on the upside or the downside? That is, if things don’t go according to the projections, is it more likely to be because the player had a breakout year, or because they fell apart?

Naturally, I had some prior beliefs about the answers to this question, but it seemed worth looking at some numbers. So–and again, this is not all that rigorous, but I still think it’s helpful–here’s what I did.

  1. I chose to measure hitting performance using wOBA, and pitching performance using FIP. These are both statistics that give a pretty good indication of a player’s performance, independent of luck and the performances of other players. They aren’t ballpark-adjusted, which is fine because I don’t want to deal with the uncertainty around how the new park will play.
  2. For each guy, I went to FanGraphs and got five numbers: the actual wOBA/FIP for 2009, and the predicted 2010 value from four different projection systems: Marcel, Bill James, CHONE, and the FanGraphs community projection.
  3. To get a sense of prediction uncertainty, I compare these four systems. The more varied they are, the more uncertain the projection. Because Marcel is just a “dumb” projection based on previous season performances, age, and regression to the mean, I treat it as my baseline, and then see how the other projections look in relation to it. If the “smart” systems generally project better numbers than Marcel, I take that as evidence of uncertainty on the upside. If they project worse numbers, I take that as evidence of uncertainty on the downside.

Now, to the numbers. First, the hitters:

Predicted wOBA, Twins hitters

wOBA is scaled to correspond to on-base percentage, so basically 300 is really bad, and 400 is really good. But it’s not the levels we’re interested in, it’s the uncerainty.

The projections are the most spread out for Hudson, Hardy, and Young. That’s not hugely surprising, since they all have major question marks attached to them. How much will Hudson decline due to age? Will Hardy bounce back from his awful year? Will Delmon ever figure it out?

On the flip side, the projections are more clustered for Morneau, Cuddyer, and Punto. These guys are known quantities–small quantities, in LNP’s case. It should be noted though, that everyone is predicting that Cuddyer will backslide from his unusually strong power numbers–nobody expects him to slug over .500 again.

Now, what about upside vs. downside uncertainty?

The guys who have a chance to put up surprisingly good numbers are:

  • Mauer. The issue is basically whether he can come close to repeating his MVP numbers, or whether he is, in fact, just a mortal human being.
  • Morneau. The upside scenario here is basically just that Justin stays healthy and his power doesn’t disappear after the all-star game. We still don’t have enough data to know whether his second half disappearing act is due to something real, or whether it’s just a coincidence.
  • Cuddyer. Basically, he would have to show that last year wasn’t a total fluke.
  • Delmon Young. This, of course, would be the scenario where Delmon finally, after all these years, shows evidence of becoming a useful player. Maybe this much-discussed weight loss of his will be the ticket, after all.

Now, as for the possible disappointments:

  • Span. This is basically just a question of what his true talent level is. Marcel thinks that overall, he’ll basically be as good as last year. The most pessimistic projection, from Bill James, has him losing both some on-base percentage and some power.
  • Hudson. When you’re talking about a middle infielder in his thirties, there’s always a risk he’ll fall off a cliff. Some age-related decline is expected, it’s just a question of how much.
  • J.J. Hardy. If you don’t believe the story that Hardy’s brutal season was mostly down to bad luck, then you might expect him to disappoint.

That covers the hitters–although note that I didn’t include Jim Thome, who could be a factor if he ends up getting significant playing time. Now on to the more interesting and unpredictable group, the starting pitchers:

Twins starting rotation, predicted 2010 FIP

Since a low FIP is better (as with ERA), being to the left is good on this graph.  And interestingly, the “smart” projections like all the Twins starters better than Marcel, with the exception of Brian Duensing (who is likely to not make the rotation out of spring training).  So there’s a possibility that the whole rotation could exceed expectations.

Unsurprisingly, the biggest wild card is Francisco Liriano. Marcel projects him to be worse than any of the other five options, and nearly as bad as he was last year. Bill James, meanwhile, projects him to be the ace of the staff. Which of these is closer to the mark is probably the biggest single factor impacting the Twins’ fate this year.

To summarize, let’s consider two possible outcomes for 2010: an overachieving Twins team that wins 95 games and makes a run at the World Series, and a disappointing year where they lose the division to the Tigers or White Sox.

The overachieving scenario looks something like this:

  • Joe Mauer comes close to repeating his MVP campaign, and shows that his newfound power was for real.
  • Justin Morneau stays strong all year, making a bid for his second MVP
  • Delmon young takes a major step forward.
  • Francisco Liriano finds his confidence and his slider, leading a starting rotation that has improved across the board.

The underachievers, meanwhile, look like this:

  • J.J. Hardy turns out to have lost it, and puts up putrid numbers again.
  • Orlando Hudson turns into a pumpkin.
  • Liriano frustrates us again, prompting most to give up on him.

Now, there are a couple of loose ends I haven’t mentioned. The first is injuries–I’ve ignored them here, but obviously if a key player gets hurt, it could change the whole season. The other question mark is a player who I haven’t mentioned, but whose future is also rather uncertain: Joe Nathan.

Last year, a lot of people, including me, started to wonder if Nathan was starting to show his age. He had some close calls and blown saves, and gave up home runs at the highest rate of his Twins career. It made me start to think that maybe the Twins had made a mistake by not trading Nathan at the peak of his value, since closers tend to be over-valued anyway.

Looking at the projections doesn’t really clear things up. Marcel expects Nathan to post his worst FIP since becoming the Twins’ closer, based on extrapoliting his declining strikeouts, rising walks, and rising home run rate. The “smart” systems are much more favorable however–CHONE and the fans expect more or less a repeat of last year, while Bill James gives Nathan his best FIP since 2006. Compared to Liriano and some of the hitters, I don’t think this is quite as big an issue for the team, but it will certainly be an aggravating year if Twitchy suddenly starts to look like a question mark in the ninth inning.

We’ll just have to wait and see–in just another month, we’ll be done with meaningless spring training games and we can start to see which of these storylines will play out.

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