Since Moneyball came out it has pushed not only OBP and OPS into the limelight, but also intrigued a whole new group in advanced statistical analysis. It’s fairly safe to say at least two-thirds of the league now employ and understand these numbers and look for bargains according to them.

The problem is it now is much more difficult to gain the services for cheap of someone like the Scott Hatteberg’s of the Moneyball era. If everyone knows your strategy then you no longer hold an advantage and are forced to overpay for what you know.

The idea of Moneyball was to see what skill the league as a whole was undervaluing and exploit it by paying a lower cost for that skill. That new skill according to many is defense. We can see that by looking at a team like the Seattle Mariners who added 24 wins this year while letting players like Raul Ibanez walk for defensive minded players like Franklin Gutierrez.

We can attempt to see how the league has grasped this recently using team UZR/150 numbers. I ran a year-by-year correlation on these numbers and found an interesting trend. Here are the r-values for 2002-2007:

2002-2003 = 0.364
2003-2004 = 0.451
2004-2005 = 0.504
2005-2006 = 0.347
2006-2007 = 0.389

There is some variance year to year, but the trend seems to show that some teams prefer to stay, as they are whether that is good or bad. Teams had a fairly strong chance of staying at the same level of defense for these 5 years. Then something changed in 2008 as the r-values mad a huge change:

2007-2008 = -0.168
2008-2009 = 0.114

Suddenly your defense from the year had very little to almost a negative correlation with the previous season. This could be many factors like random free agent turnover, targeting defensive players or even bringing up younger talent.

I think we have some evidence of the younger player theory as the league age of position players increased to a high of 29.3 in 2004 and held at 29.1 until 2007. It then dropped to 28.8 for 2008 and 2009. This gives some evidence on the willingness of teams to go with younger talent. Whether or not they understood their ability to be better defensively is still in question, but it has shown to work for some teams.

There are some teams who have yet to catch on to the trend though. In the past 2 years the Blue Jays, Cubs, Indians, Marlins, Mets, Nationals, Royals, Twins, White Sox and Yankess have trended down or held poor team UZR/150. The Yankees have actually been one of the worst defensive teams since UZR has been calculated with an average UZR/150 of –8.375 from 2002-2009. They have preferred to spend their money on aging sluggers, which will of course lead to poorer defensive numbers.

I’m interested to see where this trend goes in 2010. As we establish which teams are better at consistently producing solid defensive teams we may see year to year correlation of UZR/150 again. We could then solidly identify what teams are targeting defense that we might not think are.

The three most improved teams in 2009 where the Mariners, Reds and Tigers. I am surprised to see the Reds, but they followed the pattern of going younger and allowing aging players to leave much like the Mariners. Will they continue to be this good defensively in 2010?

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