The Arizona Diamondbacks have had two seasons that pretty much defy their actual run differential. That defiance was good in 2011 and not so good in 2012. The similarities between the offense was minimal. The Diamondbacks scored 734 runs in 2012 and 731 in 2011. The pitching was not that far off either. The pitching allowed 688 runs in 2012 compared to 662 in 2011. And yet in 2011, the Diamondbacks should have won 88 games and won 94 and should have won 86 games in 2012 and won only 81. Was the team lucky in 2011 and unlucky in 2012? Perhaps. But from what I can see, the difference was the defense.
Before we look closely at the difference in the two years from a defensive standpoint, let's look at some circumstantial evidence. The real striking Exhibit A is how the team fared in one-run games. The two seasons are a mirror image. In 2011, the team went 28-16 in one run games and 9-4 in extra inning games. In 2012, the team went 15-27 in one-run games and 3-4 in extra inning games. Again, you can chalk that up to luck and the bounce of the ball. But this, to me, is circumstantial evidence of a deeper problem.
The Diamondbacks as a whole team had a +30 score overall for total zone runs saved over average in 2011 (baseball-reference.com). That figure fell to -6 in 2012. The glaring difference was the outfield. Many Diamondback fans dislike Chris Young and cheered when he left the team this off season. But he was spectacular in 2011 and by missing much of 2012, the center field defense suffered. But the biggest difference was in left field. Gerardo Parra played 128 games in left field in 2011 and left field in total had a fielding score of +11 over the course of that season.
Enter Jason Kubel in 2012 and the outfield defense crumbled. Kubel scored a -12 all by himself. Parra played about eight percent of the innings in left and at least pulled the total up to a -6. But that is a twelve run swing from one year to the next.
The injury to Stephen Drew hurt too. Drew has been an underrated defensive player in a league dominated by Tulowitzki and Rollins. But the shortstop play in 2011 was rated at zero. In other words, based on an average, the D-back shortstops did not cost their pitchers any runs nor saved them any against the league average. In 2012, that figure fell to -6.
Can we see a difference in outfield play in the record? Again, this isn't a one to one cause and effect, but when Arizona pitchers allowed a fly ball in 2012, the opposing batters batted .238 with an OPS of .882. On line drives, the OPS against was 1.730. In 2011, opposing batters batted .209 with an OPS of .770 on fly balls and had an OPS of 1.676 on line drives. Clearly, outfield defense had to have some effect on those numbers.
Keep in mind that the team's workhorse, Ian Kennedy, is a fly ball pitcher. Was the difference in his pitching from 2011 to 2012 the defense? I think a case can be made. The team's other young pitcher, Daniel Hudson, was also a fly ball pitcher before he went down with his elbow. And Josh Collmenter? He is one of the most dramatic fly ball pitchers in baseball and his outfield defense could not have helped him during his disappointing 2012 season.
Losing Young to injury last season probably cost the Diamondbacks two to three wins. Losing Parra's full time defense and adequate offense to Jason Kubel's bad defense cost the Diamondbacks another two wins. That kind of stuff goes a long way in telling a story about how a team can beat its run differential so well in 2011 and then lose to its differential the following season.
As of right now, Kubel is still the projected left fielder for 2013. Cody Ross takes over in center and he isn't bad out there and has had some decent seasons. But even Ross's best season does not add up to Young's two best seasons. It seems the Diamondbacks had a winning formula in 2011 and should have stuck with it.