Colby Rasmus, the Astros, and Strikeouts

I don’t think one should require much convincing that the Houston Astros are taking a worthwhile shot in signing Colby Rasmus. Most simply, it’s a one-year contract for a 28-year-old, and it’s worth just $8 million. Rasmus has had a volatile career — last year he finished with a .287 OBP — but he was still overall an average hitter. The season before, he was a lot better than that. The Astros had a role for Rasmus, after dealing Dexter Fowler. If he’s good, he’ll help. If he’s really good, he’ll be worth a qualifying offer. If he’s bad, well, lots of Astros have been bad, and Rasmus alone won’t stop the Astros from getting where they’re trying to go. At the end of the day, 2015 is just a season the Astros have to play out before the seasons they want to play out.

So I don’t think the contract is necessarily that interesting. Rasmus is talented, and he’s trying to bounce back. The Astros, as a team, aren’t as good as the Mariners, Angels or A’s, so it seems like they’ll be fighting the Rangers for fourth in the American League West. A year from now, I doubt we’ll be thinking much about this. But there is one interesting note we can discuss in more detail: Rasmus strikes out a lot. Several Astros strike out a lot. It seems like the Astros are going to strike out a lot.

The caveat is that the season hasn’t started yet, so we don’t know what else the Astros might do, but let’s consider the current projected team depth chart. Rasmus is on it, as a regular. George Springer is on it, as a regular. Also, Evan Gattis. Also, Chris Carter. Also, Jon Singleton, to some extent. I pulled up each player’s 2014 contact rate, and then I weighted those by projected 2015 playing time. The result: a team contact rate of 74.5%. That assumes no changes from last season, but contact rate is a pretty stable metric.

Just last year, the Astros struck out 23.7% of the time as a team, a rate that was 2.2 standard deviations higher than the mean. Below, a table of projected 2015 team strikeout rates, with the corresponding standard deviations. Note that projections are based on Steamer and the depth charts, and for now, Steamer is projecting lower-than-expected strikeout rates across the board, by more than a full percentage point. So, the most important thing here is the standard-deviation column.

Team Projected K% St. Dev.
Astros 22.6% 2.5
Cubs 22.0% 2.1
Padres 20.8% 1.3
Marlins 20.6% 1.2
Reds 20.4% 1.0
Orioles 20.0% 0.8
Yankees 19.9% 0.7
Twins 19.6% 0.5
Angels 19.5% 0.5
Mariners 19.3% 0.3
Pirates 19.1% 0.2
Rays 19.0% 0.1
Mets 18.9% 0.1
White Sox 18.9% 0.1
Dodgers 18.8% 0.0
Diamondbacks 18.7% -0.1
Rockies 18.6% -0.1
Indians 18.5% -0.2
Rangers 18.1% -0.5
Nationals 18.0% -0.5
Brewers 17.9% -0.6
Phillies 17.9% -0.6
Braves 17.8% -0.6
Tigers 17.7% -0.7
Blue Jays 17.7% -0.7
Cardinals 17.5% -0.8
Red Sox 17.3% -1.0
Athletics 16.4% -1.6
Royals 16.3% -1.6
Giants 16.1% -1.8

The Astros are projected to strike out more than anyone. It’s them, then the Cubs, then a gap between second and third place. I noted that, last year, the Astros’ team strikeout rate was 2.2 standard deviations higher than the mean. This year they’re projected at +2.5, which is obviously even higher. So the Astros are projected to strike out a bit more, relative to the league.

As a quick aside, look toward the bottom of the table. Four teams in particular project to substantially reduce their strikeout rates. Those teams, compared to themselves in 2014:

  • White Sox: -1.4 standard deviations
  • Giants: -1.4
  • Braves: -1.6
  • Red Sox: -1.9

Last season, Boston’s strikeout rate was higher than the mean by 0.9 standard deviations. Their Steamer projection: lower than the mean, by 1.0 standard deviations. It’s the biggest projected change in baseball. It’s not surprising to see the Giants, given the additions of Nori Aoki and Casey McGehee. Nor is it surprising to see the Braves, who this year are going to be differently bad.

Back to Houston. They did bring in Jed Lowrie, who doesn’t strike out too much. Hank Conger’s strikeouts are manageable. Luis Valbuena is pretty good at putting the ball in play. You’ve seen enough of Jose Altuve to know of his skills. The strikeouts aren’t going to be completely out of control. But, there’s always some concern that the offense might ultimately underachieve, because of all the whiffing. This comes up frequently when a team looks like it’s going to have a whiffing problem. I, personally, don’t think there’s much of anything to worry about.

Here’s an obvious graph: wOBA and runs scored are very closely related. From the past decade:


That’s about as strong as a relationship ever gets, as baseball analysis is concerned. Runs are one measure of offensive productivity. wOBA is another such measure. One is a lot like the other. This doesn’t even bother to consider baserunning, but that’s almost always a minor thing.

Anyway, based on the runs/wOBA relationship, we can use wOBA to calculate an “expected runs” figure. I think I’ve done this very analysis before right here on FanGraphs, but I don’t remember if or when, so, here we are. Once we have expected runs, we can calculate the difference between expected runs and actual runs. Regarding these differences: is there any relationship between the differences and a team’s strikeout frequency? I’ve created a simple measure we’ll call K% Index, which is just team K% divided by league K%. So, a K% Index over 1 indicates a team that struck out a lot. The opposite is the opposite.

Turns out, yeah, no, nothing to speak of.


It’s a total mess. A total, random mess. High-strikeout teams have under-performed; high-strikeout teams have over-performed. Low-strikeout teams have under-performed; low-strikeout teams have over-performed. There is no observable relationship. Whatever the Astros end up expected to score, they should actually score something close to that amount. It doesn’t matter if they strike out 25% of the time.

There is something that’s missing. This analysis has considered after-the-fact relationships. What about players on teams projected to strike out a lot, and players on teams projected not to strike out a lot? Do players on strikeout-prone teams under-perform offensive projections? Do players on contact-heavy teams over-perform offensive projections? I don’t have an answer to these questions right now. Maybe someday I will. But I haven’t read anything convincing on the matter. I assume there’s nothing meaningful to it. I’ll believe the opposite when I have reason to do so.

As of this moment, based on Steamer and the depth charts, the Astros are projected to be 13 runs better than average, swinging the bat. For the most part they’ve built an offense around power, and they’re going to score runs because they’re going to hit dingers. At the same time, the Astros are projected to lose more games than they win, with a corresponding negative run differential. It’s not the strikeouts that are likely to hold them back from 2015 contention. Rather, it’s that it looks like the Astros have a relatively weak defense, and they also have a relatively weak rotation, particularly after the first couple guys. The product is getting better. Colby Rasmus should be good for the product. Yet the product isn’t yet better enough. The good news, perhaps, is no one thought it would be.

Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

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Fergie's boys
8 years ago

Are those numbers updated with yesterday’s trade? Given that Fowler strikes out a bit more than Valbuena the Cubs and Stros may be in a dead heat for most strikeouts.

As a Cubs fan I’ve been watching with interest as the Cubs seemingly ignore K rate for their draft picks and acquisitions during this entire rebuild. I’m a bit squeamish about whether its going to work out. I guess this winter the Stros just decided to join the party with the Gattis and Rasmus acquisitions so they can double the sample size of teams that strike out at a 22% rate yet still hope to win.

After watching a post-season where the teams that put the ball in play the most walked away from seemingly better teams I’m a little skeptical about whether this experiment will work.

8 years ago
Reply to  Fergie's boys

I pointed this out yesterday in response to Jeff’s earlier post about the Giants’ signing Aoki, but it seems to me that the Giants have been making a point the past several years to target not just high contact hitters but hitters who use the whole field (and therefore less prone to shifts). They may be wrong in focusing on contact rate, since as Jeff’s graph indicates there seems to be no relation at all between K% and run scoring, at least in the regular season. But it is often mentioned as one possible reason the Giants have been successful in postseason and the interesting thing to me is that the Giants themselves seem to believe it’s true.