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Three Astros Sabermetric Things

Musings About Rasmus, Aging, and Statcast

Thomas B. Shea-USA TODAY Sports

What does the holiday season bring to mind?  Leaving cookies and milk for Santa. Plum pudding.  The Nutcracker.  Sabermetrics.

Oh, Okay, scratch sabermetrics.  We can talk about sabermetrics any time of the year.  Maybe you will get some time to relax during the holidays.  That's a good time to talk baseball numbers.  I put together three nuggets of information related to sabermetrics, with a special slant toward the Astros.

Colby Rasmus

Colby Rasmus accepted the Astros' qualifying offer; we know he will be back with the Astros.  Rasmus provided versatility in the outfield;  personally, I'm glad he is coming back.  Offensive power was a big part of the Astros' profile in 2015, and Rasmus provided power which would have been difficult to replace.  Rasmus led the Astros in isolated power (ISO) at .236. According to ESPN Home Run Tracker, he was tops on the team in "no doubter" HRs and third in average HR distance.

The question is whether the 29 year old Rasmus will continue his power output in the coming season.  After all, he posted the highest ISO and HR total of his career in 2015.  The Steamer projection system projects an abrupt drop-off in power (a .188 ISO which would be his lowest in three years) and OPS (.702--compared to .789 in 2015).   The no-frills Marcel projection method projects power and OPS (.783) more in line with 2015.

In a preseason profile in 2015, I suggested that most of the projection systems were understating Rasmus' likely power numbers.  I think that continues to be true for the 2016 Steamer projection.  The reason: Rasmus' power has been significantly higher over the last three years, relative to the earlier part of his career.

Rasmus' HR per flyball ratios are summarized below.


2009-2012 Avg.  11.5%

2013-2015 Avg.  18.1%

2015  17.6%

Rasmus' ISO is summarized below.

Isolated Power

2009-2012 Avg.  .180

20013-2015 Avg.  .228

2015   .236

In summary, Rasmus' 2015 power indicators are firmly within the range of the previous two years, but much higher than earlier in his career.  In part, the distinct change in power indicators (for 09-12 vs. 13-15) reflects the fact that Busch Stadium was a more difficult venue for HRs (No. 23 in HR park factor). Minute Maid Park and Rogers Center are No. 9 and No 15 in HR park factor.  But it appears that Rasmus has undergone a maturation in his power output.  As this Baseball Prospectus article states:

Hitters peak in batting and slugging average at 28 while continuing to improve in their home-run hitting and walking abilities until 30 and 32, respectively. Home runs rising beyond the peak for doubles and triples indicates that foot-speed on the basepaths fades before hitting power. In addition, batters may be using veteran knowledge to better manage the strike-zone-or possibly becoming more friendly with umpires-to walk more and hit with power as they age.

This late 2015 fangraphs article indeed suggests that Rasmus is using his veteran wits to alternate batting stances in a "chess match" with pitchers and catchers. The later peak for power hitting and drawing walks is the basis for so-called "old man skills," which lead to the home runs and walks profile. My take: Rasmus should provide power output in 2016 which is at least comparable to 2015.

Bringing up the subject of old man skills and player aging is a good segue to the next topic.

Do Red Flags Exist for Future Batter Deterioration?

I often use the phrase "fall off a cliff" to refer to batters who face an extreme and abrupt age-related decline in hitting skill.  It would be useful if we could identify signs that a player has a higher risk of falling off a cliff.

Jeff Zimmerman at Fangraphs/Rotographs has identified a potential red flag, discussed in this article.  After reviewing the abrupt decline of J.J. Hardy, Zimmerman noticed that the fall was preceded by significant declines in Pull% and Contact%.  He postulated that reduced ability to pull the ball and make contact is an indicator of diminished hitting skill.  He performed an expanded analysis, and found:

Once a player starts seeing a decline in Pull% and Contact%, their power and overall production decline more than average and there seems to be no regression/bounce back the next season.

Notably, this "red flag" should be considered as a tentative sign, since, at an individual level, other factors may explain the decline in Pull% and Contact%.  Having said that, Zimmerman identified a number of batters--some surprising, some not--who exhibited this red flag last season.  Notable names include Hunter Pence, Matt Holliday, Kole Calhoun, Matt Carpenter, Ryan Zimmerman, and Jayson Werth.

Only two Astros were on his list: Hank Conger and Chris Carter.  Interestingly, both players were non-tendered this off-season.

Let's consider some other Astros' hitters who might be at risky ages.  We just discussed the effect of aging on Colby Rasmus. Rasmus increased his Contact% and Pull% last season. Jason Castro had a lower Contact%, but did not decrease his Pull%.  Carlos Gomez exhibited a lower Pull% but increased his Contact%.  Luis Valbuena showed a small decline in both Pull% and Contact%, but the effect was far below the 10% threshold used by Zimmerman. Evan Gattis decreased his Pull% but also increased his Contact%.  With the exception of Valbuena, none of these batters experienced a combined decline in Contact% and Pull%, and in his case, the decrease was too small to trigger concern.

Do you find it interesting that the only Astros' batters with this red flag are not returning to the Astros?  Did the Astros perceive a similar risk with Conger and Carter?  Or, equally plausible, it's just a coincidence.

StatCast Review

This was the first year for StatCast, which used cutting edge technology to provide public information measuring various skills, like foot speed and exit velocity.  The MLB Network provided its review of StatCast highlights last week.  In case you missed it, the video is available here.

From an Astros' standpoint, the most noteworthy discussion was the praise given to Carlos Gomez's arm.  Gomez exhibited the highest exit velocity (103 mph) on throws from the outfield. The show says this is like putting Aroldis Chapman in the outfield.  In addition, Jake Marisnick was among the leaders in outfielder exit velocity.  The show points out that the Astros' outfield is loaded with throwing ability, with George Springer--who has an outstanding arm--only the third best arm.