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The Rasmus File

Astros Sabermetrics: What Can We Expect From Colby Rasmus in 2015?

Rasmus - Sabermetrics Article

Colby Rasmus was one of the more interesting signings of the Astros' off-season.  The talented outfielder has been a difficult baseball player to predict over his career.  Astros' GM Jeff Luhnow knows him well, since he was responsible for drafting him as the Cardinals' first round pick in 2005.  The one year contract represents an opportunity for both the Astros and Rasmus.  Rasmus has an opportunity to re-establish himself in the free agent marketplace.  For the Astros, Rasmus' upside could make him an undervalued asset. If Rasmus plays to the level of his 2013 season, it would be a game-changing boost to the Astros' record.. In addition,  I'm sure the Astros would be happy if Rasmus played so well that he is worth a qualifying offer after this season.

Although Rasmus' 2014 results fell below expectations, he still had the capability to live in pitchers' fitful nightmares.  For instance, consider the grand slam he hit against Edison Volquez in May, 2014, which appears above.

Recent articles have described Rasmus as an enigma.  Injuries and year-to-year inconsistency have plagued his career so far.  The word "potential" accompanies almost any write up of Rasmus.  And the perception of Rasmus probably has suffered because of the lofty expectations.  Rasmus at one time was the No. 1 hitting prospect in baseball.  Some scouts compared him to Hall of Famer Frank Robinson.

Let's examine what we can expect from Rasmus by using some sabermetric tools.  This won't produce a definitive answer, by any stretch of imagination, but it may provide us some clues.

Rasmus' Performance History

Feel free to peruse Rasmus' player page at Fangraphs.  Rasmus' career stats paint the picture of a solid outfielder with good defensive skills, slightly above average offense, good power, below average batting average, decent but not elite walk rates, and worse than average strike out rates.

Rasmus-Career Through Age 27
8.60% 25.20% 0.192 0.298 0.246 0.313 0.438 0.751
0.326 103 14.4 23.5 6.9 13.4 lists comparable players through age 27 which range from scary (Chris Young) to exciting (Dwight Evans, Ron Gant, Tommy Agee).  However, the career stats don't reveal why Rasmus has been described as an enigma.

So far, Rasmus' year-to-year results have been erratic.  Rasmus has two seasons of elite level performance--2010 (age 23) and 2013 (age 26).  In 2010 and 2013, he posted, respectively, a wRC+ of 130 and 129 and a WAR of 4.0 and 4.8.  In three seasons, 2009, 2011, and 2012, he posted below average offensive results (wRC+ of 82 - 90) with WAR ranging from 0.5 to 2.6.   Last season was disappointing compared to the excellent 2013 performance, but he managed to post slightly above average offensive results (103 wRC+).    His WAR in 2014 was only 0.6, in part due to weak defensive metrics and in part to injuries which limited him to 104 games.


I have compiled several projections for Rasmus' 2015 season from reputable sources.  I do not have a ZIPS projection for Rasmus.  The projections are compared to Rasmus' actual 2014 results, an average of the projection sources, and a simple weighted average projection method.  wRC+ and WAR (WARP in the case of Davenport) are provided only if available. If you want to know more about projections, ESPN has a discussion of the process behind baseball projection systems.

Rasmus 2015 Projections

Fantasy Pros Consensus
20 0.233 0.294 0.431 0.725
Davenport (50% cum. prob.) 20 0.236 0.301 0.429 0.730
22 0.231 0.298 0.418 0.716 102 1.9
18 0.238 0.302 0.439 0.741

Fangraphs Fans sourcing
21 0.248 0.305 0.449 0.754 112 2.3
AVERAGE OF ABOVE SOURCES 20.2 0.237 0.3 0.433 0.733

2014 Actual Season Results 18 0.225 0.287 0.448 0.735 103 0.6

Three Yr. Weighted Avg. Method

0.762 108

First, some explanations are in order.  The Fantasy Pros web site provides a consensus based on a number of projection systems.  Clay Davenport's projection provides predicted results at various cumulative probability levels.  I chose the 50% level, because an equal probability (50%) exists that the results will be higher or lower than that level.  The Fans projection is based on crowd sourcing expectations of Fangraphs readers.  Because the fans submitted projections while Rasmus was still a free agent and not associated with a team, I believe fan bias is minimized.  In general, the average of projections expects Rasmus to decline from his 2014 results.  The Fans projection is considerably more optimistic than the projection systems.

For comparative purposes, I have shown Rasmus' recent OPS and wRC+ using a simple three year weighted average method.  This procedure, sometimes called a "poor man's regression," is based on a weighted average of the most recent three years' performance (2012 - 2014); the weighting is 3-2-1, respectively, from most recent to least recent season. This simplistic approach produces a result more optimistic than any of the projections.  I am not suggesting that this should be regarded as better than, or equivalent in quality to, the projection systems.   However, the differences between the projections and this method may illustrate the weight that projections place on factors other than the raw numbers in the most recent three years. Since projection systems generally rely  most heavily on recent career performance, the higher result based on a simple three year weighted average suggests that other factors, such as age-related regression, BABIP regression, or assumptions regarding continuing decline in run environment, are suppressing the projections of Rasmus' 2015 performance.

The table below compares the Rasmus projection for 2014 to the 2015 projection.  The 2014 projection followed Rasmus' excellent 2013 performance, and anticipated a robust 2014 performance, while the 2015 projection follows a lukewarm 2014 season, resulting in a projection of results generally worse than 2014.

2014 vs. 2015 Projections

2014 OPS Proj. 2015 OPS Proj. Difference
Clay Davenport




Fangraphs Fans sourcing


This tells us that examining Rasmus' decline between 2013 and 2014 is important in evaluating the potential for Rasmus to exceed the projections.  In the absence of that season's decline, the projections for Rasmus would be considerably better.

Beyond the Boxscore published an article discussing Colby Rasmus' own evaluation of the 2014 season. Rasmus called 2014 a "crazy year," pointing to injuries associated with playing on artificial turf, bad luck on hard hit balls, and a weak BABIP caused by the extensive defensive shifts that he faced.

"I believe I had my highest percentage of hard balls or line drives since I've been in the big leagues but the lowest average on balls in play. That's been tough and I don't think I've been through a stretch like that in my career to where balls that I've hit hard have been caught so's been a struggle to not try to do too much up there because I've hit so many balls hard and hit into the shift or whatever."

Rasmus notes that many factors are involved, but chalks it up to "it just wasn't my year."   As an initial fact check: Rasmus is correct that he had the highest line drive rate of his career in 2014; however, 2014 is not the lowest BABIP of his career, though it is below his career average.


A significant part of Rasmus' seemingly erratic year-to-year performance is associated with a highly variable Batting Average on Balls in Play (BABIP).  Rasmus' two best seasons (2010 and 2013) were also his two best BABIP seasons, with a BABIP in the .350 range.  However, his BABIP has fluctuated within a wide range in his other seasons.  Line drive rate is a significant driver of BABIP, and line drives and flyballs are an above average part of Rasmus' batted ball profile.  Flyballs tend to reduce BABIP, while line drives will increase BABIP.  Because line drives are a smaller sample of batted balls, line drive rate will show variability from year to year.

Pop ups are another factor which suppresses BABIP.  Subsequent to arriving in Toronto, Rasmus' pop up rate increased to double digit rates each year.  It isn't unusual for a flyball hitter to experience a high pop up rate.  However, because pop ups are also a small sample of batted balls, the rate will also fluctuate each year, adding to BABIP variability.  It is unclear whether Rasmus' infield flyball increase after he left St. Louis is associated with a change in ballparks or a change in approach. Foul pop ups are a subtantial part of the infield flyball rate, and this can be influenced by the ballpark.  Based on foul outs at Minute Maid Park and Rogers Center in 2012-13, my conclusion is that moving to MMP could reduce Rasmus' foul outs by 15%.  However, given the small numbers (foul outs are only a portion of infield flyballs, which are a small sample of batted balls), I don't have a high level of confidence that this reduction will be noticeable.

Rasmus had a .294 BABIP in 2014, which is below his career average, but not a huge decrease from his career average (.299).  However, his 2014 BABIP represented massive regression from his .350 BABIP in 2013. Rasmus' 2013 BABIP probably was unsustainably high, but there is reason to believe that his 2014 BABIP is not representative of what he can do in the future.

Rasmus' BABIP in 2014 should have been significantly higher than .294, based on x-BABIP.  x-BABIP stands for "expected BABIP," and is used to estimate whether the player was helped or hurt by random luck.  Jeff Zimmerman at Fangraphs has developed an x-BABIP which includes variables for Inside Edge data regarding how hard balls are hit and player speed, as well as data on the types of batted balls.  In theory this should be a superior advancement in estimating BABIP.  Jeff Zimmerman's x-BABIP for 2014 is revealed here.  (Spreadsheet is here.)

Based on Zimmerman's x-BABIP, Rasmus' 2014 BABIP should have been .329, which is 35 points higher than his actual BABIP.  This provides some support for Rasmus' belief that he was unlucky, with hard hit balls falling into gloves.

It's possible that a portion of the gap between x-BABIP and actual BABIP could be attributable to increased use of defensive shifts.  Rasmus indicates that the shifts were frustrating. Using Brooks' Baseball spray charts, we can compare 2013 and 2014.  On the surface, there doesn't appear to be  major difference in groundballs to the shift side--Rasmus pulled the ball and sustained a large number of groundball outs in both years.  However, using an app created by Bill Petti and Jeff Zimmerman, we can isolate line drive outs.  In 2014, it appears that Rasmus sustained 6 more line outs in the vicinity of the shift compared to 2013.  Six batted balls may not seem like a lot, but each one is a significant reversal of run expectancy.  Considering that the six lost hits occurred in about one third fewer plate appearances compared to  2013, we can understand why Rasmus may feel like the shift was a big problem.  It's also possible that the shift got into his head and affected performance more than it should.

According to Baseball-Reference's splits page, Rasmus had a .676 BABIP on line drives compared to a .737 career BABIP on line drives.  This also seems to confirm Rasmus' view that he hit the ball harder than ever but more of those batted balls were caught.  Some of this effect may be better designed shifts as well as just random bad luck.

Hopefully the Astros' batting coaches will study the impact of defensive shifts to determine whether Rasmus should attempt to counter the shifts.  A major change in his pull hitting style may not be advisable: Rasmus' OPS on pulled balls is 1.019 and his OPS on opposite field batted balls is .529.  However, Rasmus has shown the ability to bunt successfully, and he has some power to the opposite field.  There may be some strategic occasions where Rasmus can look to use the opposite field.  Want some evidence that Rasmus has power to LF?  The HR, below, off Pirates' pitcher Cole, clears the fence in PNC Park's spacious LF.

Rasmus - Sabermetrics Article


Colby Rasmus' most significant offensive value is derived from his power.  Therefore, projecting Rasmus' future value is dependent on expectations regarding his continued ability to sustain power. At age 28, Rasmus should be close to his peak as a hitter.  But this isn't necessarily how projection systems view the future direction of his power.  For example, Steamer projects a 16% decline in 2014 isolated power (ISO) for Rasmus.  Davenport projects a 40 point reduction in SLG%.  Presumably these projections are based on age-related decline in power.  Since the Blue Jays and Astros home parks have identical 106 home run park factors for LH batters, the change in ballparks should not materially affect the power projection.

I am skeptical of the projected declines in power, because Rasmus' performance is not showing any signs of age-related diminishment of his power capability.  Average distances of flyballs and batted balls are correlated with a batter's ability to sustain power.  Colby Rasmus had the 10th highest distance on batted balls among lefthanded batters in 2014.  His average batted ball distance was in the top 25 for all batters.  Rasmus had the highest HR/flyball rate of his career in 2014.  The 2014 season marked the 2d highest ISO of his career (behind only 2013).  Power-related indicators for Rasmus are shown below.

Distance Per HR/Fly Isolated

Batted Ball
Career Avg. 200 13.7% 0.192
2013 197 17.3% 0.225
2014 202 19.4% 0.223

If anything, Rasmus' power has matured over the last two seasons.  There is little indication of a physical decline in his power.  In the gif, below, Rasmus displays his strength in April 2014 by sending a HR onto the street near the food court at Camden Yard.

Rasmus - Sabermetrics Article

Plate Discipline

The most significant question mark surrounding Rasmus' future hitting is the trend in deteriorating walk rates and higher strike out rates over the course of his career.  His 2014 walk and strike outs rates were worse than 2013.  His strike out rate of 33% was the highest of his careers.

The 2014 trend appears to be associated with a conscious decision to be more aggressive at the plate, with a swing percentage three percentage points higher than 2013.  As a result, his outside swing percent was the highest of his career.  This, in turn, led to the lowest contact percent of his career--more than 3.5 points below 2013.  The more aggressive approach may have been well-intended, but, in retrospect, it appears that Rasmus would benefit from a somewhat more patient approach at the plate.  I agree with Chris Teeter's conclusion at Beyond the Boxscore:

He did swing more in 2014 than in 2013, both at pitches in-the-zone and outside-the-zone, which might be evidence of him pressing the issue. Ironically his swinging more likely influenced his increased strikeout rate, thereby continuing the cycle of disappointment.

At some point, Rasmus needs to adopt a more selective approach and slow down the deteriorating peripheral rates.


You can form your own opinion of the projections for Rasmus' 2015 season.  My view is that the odds are fairly good that Rasmus can beat the projections.  But it may depend on how comfortable he is with the Astros' coaches, his ability to avoid injuries, and a little bit of luck.