What happened to the 2009 Angels offense?

By Andre Castillo – AngelsWin.com Feature Writer
In 2009, the Angels were the second best offense in the majors, finishing second in total runs scored with 883. This was topped only by the Yankees, who scored 915 runs that year.
In 2010 the Angels offense appeared to fall off a cliff. That year the Angels scored only 681 runs, good for just 19th in the majors. This year, the Angels are better, 11th in the majors with 143 runs, but still far off the blazing pace they set in 2009.
While we know some individuals are no longer performing, such as an injured Kendrys Morales, a departed Chone Figgins, and a declining Bobby Abreu, I wanted to stop and take a look at the team as a whole. In 2009 we heard a lot of talk about a new, more patient Angels approach at the plate. What happened to this team plate discipline? Did it disappear? Did it ever exist?

To answer this question I turned to Fangraphs’ plate discipline statistics and looked at the Angels team stats for the Bobby Abreu years of 2009, 2010 and what we have for 2011. While there are many ways to measure plate discipline, I focused whether on not Angels hitters were swinging at the right pitches. In other words, I looked at O-Swing%, the  percentage of pitches out of the strike zone that Angels hitters swung at, and Z-Swing%, the percentage of  pitches inside the strike zone that Angels hitters swung at. The findings were not what I expected.
When it comes to plate discipline, the first advice your hitting coach will give you is to lay off of pitches out of the zone. So if the key to the Angels’ offensive success in 2009 was good plate discipline, they should have a very low O-Swing%. But this wasn’t the case at all.
In 2009, the year the Angels had the second best offense in the majors, yet they ranked only 21st in the majors in O-Swing%, at 25.9%. In other words, their offensive success had almost nothing to do with laying off of bad pitches. They swung at bad pitches at a higher rate than 20 other teams in the majors, yet out scored almost all of them.
In 2010, even though the Angels’ run production tanked, the Angels actually improved their plate discipline in terms of O-Swing% compared to the rest of the league. 2010 was indeed the year of the pitcher, and overall the league O-Swing% went up, as did the Angels’, which rose to 28%. Yet that still was a big improvement in their rankings, as the Angels shot up to 9th in the league in that category.
In 2011, this flip floppy trend has continued. The Angels O-Swing% ranking went down (to 22nd) and their overall offensive rankings went up (11th in runs scored).
This is completely contrary to the conventional wisdom that the Angels offense has sputtered the last couple of years because they were aggressively swinging at more bad pitches. The reality is that the Angels were actually more patient in 2010 than they were in 2009!
So what really happened to the Angels 2009 offense?
Z-Swing% is the plate discipline yin to the O-Swing% yang. It measures the percent of pitchs that hitters swing at that are inside the strike zone. So for Z-Swing%, the higher the better. This measure is important because if we just measured a hitter’s skill by using O-Swing%, you’d find that someone like me, a terrible hitter who never swang at anything in the dim hope I would luck my way into a walk, was actually the league’s most disciplined hitter, when you really need someone who knows when to swing at a strike too. Z-Swing% does that.
Z-Swing% tells a slightly different pitcher in terms of the Angels offense and seems to correlate better with their success, though not perfectly so. In 2009, the Angels were relatively aggressive in swinging at pitches in the strike zone, ranking 10th in the majors in Z-Swing%. It still doesn’t justify such a high offensive ranking as 2nd in the majors, but it’s a start.
In 2010, the Angels actually became less aggressive in swinging at those same pitches, dropping all the way down to 28th in the majors. This perhaps had something to do with a new approach taken against Angels hitters (or better quality opponents). This would explain why a lower Z-Swing% would result in fewer runs. With the Angels getting pounded in the strike zone more often, yet swinging a strikes even less, you would expect more strikeouts, fewer walks, and fewer runs.
In 2011 Z-Swing% still correlates with the Angels offensive success, but still not terribly well. The Angels hitters have become aggressive once again and improved their Z-Swing% to 22nd in the majors. Their total offense has improved as well, climbing to 11th in total runs scored.
So far we’ve established that aggressive hitting on pitches inside the strike zone has been far more important to the Angels offensive success than laying off of bad pitches has. This is very important, and very surprising (to me at least). But that still hasn’t fully explained why the 2009 team was able to score so many runs and rank so high (2nd in the majors, compared to just 10th in Z-Swing%).
To answer this question, I searched the other Fangraphs plate discipline stats until I found one that seemed to correlate very strongly with the Angels 2009 rankings. I managed to find one: Zone%.
Zone% measures the overall percentage of pitches a batter sees inside the strike zone. So, if the Angels hitters are facing pitchers who have good control and throw a lot of strikes, the Angels’ Zone% will go up (bad). If the Angels are facing bad pitchers that throw a lot of pitches out of the zone and walk a lot of batters, the Angels’ Zone% will go down (good).
So where did the Angels rank in terms of Zone% in 2009, the year of their high powered, 2nd-ranked Angels offense?
Best in the majors, with the lowest Zone% of any team that year.
And where did they rank in 2010, the year of their precipitous offensive decline? 28th.
And this year? 22nd.
It seems to me that the biggest key to the Angels success in 2009 was simply facing a lot of bad pitching. Even though the Angels were percentage-wise swinging at a lot of bad pitches back then, they were also seeing more bad pitches than any other team in the majors. Even with a relatively poor approach, they were still able to walk a ton. Then, in 2010, when they began facing tougher pitching, the Angels were slow to adapt, and began watching more strikes go right by them than they had been accustomed to.
In 2011, they seem to have found more of a  middle ground. The pitching they’ve faced so far isn’t quite as tough as it was in 2010, but still appears significantly tougher than it was in 2009. Meanwhile, they are being slightly more aggressive in their hitting to compensate.
So is the lack of plate discipline by the Angels responsible for their 2010-11 decline? No, not really.
Surprising, isn’t it?