Astros' Pitching and Defense in the Early Going....


One of the disappointing aspects of the Astros' 1-5 start this year is the poor performance by all of the starting rotation pitchers other than Brett Myers.  Since the rotation is viewed as the one and only team strength, this is very disheartening.

How about an alternative view?  I think our perception of the pitching in the first 6 games is clouded by bad defense and perhaps some bad luck on batted balls.  Don't get me wrong---I'm not trying to excuse the pitchers.  They made some mistakes and frequently threw too few strikes.  But I am suggesting that the pitching may not have been as bad as we think, and therefore the implication for future pitching performances may not be as dire as it seems.  As for the defense, that's another matter.  I can't say whether my expectations for the defense were too high--but clearly the defense played poorly in the early going.

All of the stats I will use are prior to the Astros' win in game 6 of the season, because, as of the date for writing this article, the data I use hasn't  been updated for Thursday's game.

The Astros rank next to last in the major leagues in ERA at 8.03, behind only the Red Sox at 8.33.  The NL team with the next worst ERA is the Dodgers at 5.02.  Based on ERA alone, we would say that the Astros' pitching has been devastated.  But let me throw another stat at you: the Astros have the worst BABIP in the major leagues, .381.  Most of you know what a pitching BABIP that high implies, i.e., expect a regression toward the league mean of .300 or thereabouts.  Also, the reciprocal of BABIP is Defensive Efficiency Ratio (DER)--which also means that the Astros have the worst DER in baseball.  DER is a crude measure of team defense, but it reflects the idea that a very high pitcher BABIP can be due to poor defense.  Finally, the Astros pitchers have been giving up a lot of singles, but the hitters are not crushing a lot of extra base hits.  Despite the poor ERA, the Astros have given up only 2 HRs, which is second best in the major leagues.  79% of the hits given up by the Astros are singles, compared to a league average of 69% and the Astros' average of 68% in 2010.

An advanced statistic for measuring a "defense independent" ERA is "tERA," which takes into account the types of batted balls and the average rate of converting the batted balls into outs.  The Astros team tERA is 4.81--considerably better than an 8+ ERA-- thereby ranking 21st in the majors, and better than several NL teams (Rockies, Brewers, Dodgers).  In contrast, the Red Sox team tERA of 8.49 is similar to its regular ERA.  What can cause the gap between the Astros' tERA and regular ERA?  Three possibilities: random luck; sub-par defense; or measurement imprecision (or let's just call it sample size error). 

This is too early in the season to be putting much stock in advanced fielding metrics.  But I will do what I advise others not to do, and look at the early Defensive Runs Saved (DRS) results.  The Astros and Phillies are tied for last in team DRS among MLB clubs at -12.1.  That may or may not mean anything for the future; at this stage, the results can change significantly game to game.  But it lends support to the idea that the Astros' pitching performance in the early season was damaged by the defense.  And the early DRS results are consistent with both what we have seen with our eyes, and the Astros' MLB worst DER.

So, let's compare the Astros' starters' 2011 ERA with their 2011 and 2010 tERA:

2011 ERA / 2011 tERA / 2010 tERA

Myers 1.29 / 4.95 / 3.46

Wandy 15.75 / 2.58 / 3.77

Norris 11.25 / 5.41 / 4.14

Happ 15.75 / 6.86 / 4.10

Figueroa  10.13 / 4.36 / 4.10

Again, we already know that it's too early in the season to put much weight on any pitching stats.  But, based on the early tERA results, the ERA results for all of the starters, other than Myers, appear to overstate how badly they pitched.  Moreover, the tERA results so far are considerably closer to the tERA results from 2010. In other words, our starters may not have to adjust their pitching approach that much to get back to their performance level in 2010. The tERA for Myers indicates that he his ERA outperformed his tERA.  In part, this reflects his zero strike out game on opening day, since strike outs are a key input to tERA.

 

Now, let's turn to the Astros' defense, which may have made the pitching looking worse than it really is in the first few games.  Is the defense representative of what we should expect from the Astros in the future?  I don't know the answer. When I prepared my WAR projection for the Astros before the season started, I expected the Astros to be +1.7 as a team on defense.  As I look at the early returns this season, I wonder if I was overly optimistic about the defense.

Therefore, I re-ran the calculations to look at the sensitivity of the Astros WAR projection to worse defense.  I made the worst Astros' defenders--Lee, Johnson, and Sanchez--in my previous analysis much worse.   My WAR projection assumed some improvement from last year's defensive runs saved for those three players, and perhaps that was optimistic.  In order to fill out the pessimistic defensive case, I trimmed back the defensive projections for almost all the players, making the great defenders (Bourn and Barmes) less great and changing some of the presumed above average defenders to average or below average.

The result of this more pessimistic defense projection is to reduce the Astros' projected record from 77 wins to 74 wins.  I'm not changing my original projection.  But if you think that the Astros' recent defensive lapses foretell a bad defensive team, that may cost the Astros three wins.

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