Brett Gardner and Positional Adjustment: CF vs COF

Brett Gardner is the typical center fielder, with speed and range in the field. The New York Yankees just signed him for a four-year extension of 52 million dollars, but to play left field alongside Jacoby Ellsbury instead of center field. There are concerns that Gardner’s bat may not play in a corner outfield spot, that his value would be lower at LF than at CF. This is the effect of the positional adjustment. As a player’s fielding contribution is compared to other players of the same position, we have to adjust our evaluation of a player based on where he plays in the field. The established positional adjustment has a CF getting a boost of +2.5 runs over a full season while a LF or RF gets a penalty of -7.5 runs. In theory, a CF moving to LF would gain 10 runs in the field to make up the difference, as they are now compared to worse fielders. I will be testing whether this statement holds true in reality.

I will be following Tom Tango’s methodology closely as described here. In fact, this is exactly the method Tom Tango came up with the positional adjustment we use today. I am just adding in more years of information to verify that those constants still hold true today as in 2008 when Tom Tango established the current values. I will only be looking at outfielders today and I am treating RF and LF as equal. I looked at all players who had at least 100 innings played in CF and in LF and RF combined (Corner outfield, or COF) from 2003 to 2013. I weigh each player’s UZR/162 games using the harmonic mean of their innings in CF and in COF.

Here are the results: As a group, these players average -3.6 runs/162 games in CF and +6.3 runs/162 games in COF. This is almost exactly the difference of 10 runs between the positional adjustments for CF and LF/RF. Furthermore, this has not even addressed the difference in the number of opportunities for CF and COF. Look at the following distribution of balls to the outfield from 2003 to 2013:

By the number of balls in each position’s zone, CF has about 14% more opportunities than RF and 19% more opportunities than LF. By the number of plays made by each position, CF has about 26% more opportunities than RF and 34% more opportunities than LF. This is the true reason why a CF moving to COF would suffer a decrease in value, the reduction in the number of opportunities. However, the data shows that even with the decrease in opportunities, the 10 runs difference in the positional adjustments captures almost perfectly the move from CF to COF or vice versa.

In fact, Gardner has already shown up in this sample twice, in 2008 and 2010. Over his career, Gardner has played 2295 innings in LF with a UZR/162 of 39.4 and 2353 innings in CF with a UZR/162 of 11.6. Gardner’s past actually reflects a larger difference in UZR/162 at LF and CF than suggested by the positional adjustment. Yankees fans do not have to worry that Gardner will lose his defensive value due to the move to LF. If anything, LF may be Gardner’s more valuable position and moving to LF might raise his total value instead of dropping it.

All statistics courtesy of Fangraphs.