Over the last two articles, I’ve looked at various methods for
removing some of the complicating factors when looking at team defense.
Based on the idea that team defensive metrics were really a measure of three
separate factors (park, pitching, and actual defense), we determined one way
to remove park factors (PADE: Park Adjusted Defensive Efficiency) and another to remove pitching factors (PIDE: Pitching Independent Defensive Efficiency).
By removing these outside influences in our defensive metrics, we’ve leveled
the playing field, allowing us to better judge which teams have the best
team defense, based simply on the percentage of balls in play that they
convert into outs.

With both PADE and PIDE, we removed one factor, but not both. We were
able to see either how a pitching staff and defense together looked compared
to the league or how a defense and park looked against the league. What we
did not have was one metric that simply measured defense versus defense, our
ultimate goal.

To produce that metric, we have to move back a step. Rather than looking
at the final result of PADE and PIDE, we need to look at their baselines–the expected performance of the defense based on either the pitching or
park. These baselines were included in the PIDE column as Team Expected In
Play Average (tExIPAvg), but were not included in the PADE article. Here
are both baselines, side by side:

Team                   BasePIDE       BasePADE
Anaheim Angels           1.0026         0.9992
Arizona Diamondbacks     1.0087         0.9893
Atlanta Braves           0.9917         1.0042
Baltimore Orioles        1.0113         1.0093
Boston Red Sox           1.0085         0.9905
Chicago Cubs             0.9924         1.0062
Chicago White Sox        1.0045         1.0049
Cincinnati Reds          0.9939         1.0051
Cleveland Indians        1.0007         0.9990
Colorado Rockies         1.0110         0.9794
Detroit Tigers           0.9883         1.0028
Florida Marlins          0.9989         1.0025
Houston Astros           0.9786         0.9951
Kansas City Royals       1.0009         0.9886
Los Angeles Dodgers      0.9958         1.0127
Milwaukee Brewers        0.9953         1.0072
Minnesota Twins          1.0055         0.9942
Montreal Expos           0.9886         0.9999
New York Mets            0.9988         1.0064
New York Yankees         0.9952         1.0082
Oakland Athletics        1.0111         1.0074
Philadelphia Phillies    0.9781         1.0117
Pittsburgh Pirates       0.9905         0.9988
San Diego Padres         1.0004         1.0076
San Francisco Giants     1.0097         0.9987
Seattle Mariners         1.0310         1.0104
St Louis Cardinals       0.9971         1.0020
Tampa Bay Devil Rays     1.0209         0.9961
Texas Rangers            0.9927         0.9910
Toronto Blue Jays        0.9972         0.9963

As before, the higher the number, the easier things are on the defense.
Typically, when applying park factors or other adjustments to statistics, we
simply multiply the park factor to get the adjusted statistic. However, our
park and pitching factors are reversed, with higher numbers representing a
higher standard for the defense. In order to make our measurements
accurate, we’ll multiply by the inverse of the baseline. This calculation
makes our formula for determining Team Adjusted Defense (TAD):

TAD = Def_Eff * 1/(BasePIDE) * 1/(BasePADE)

It should also be noted that when generating adjusted statistics, the
park factor is halved before multiplying. This adjustment is made because
we’re using the player or team’s home park factor, yet teams only play half
of their games at home (excepté les Expos). That adjustment doesn’t need to
be made to either PIDE or PADE. PIDE involves pitching; teams play all 162
games behind the same pitching staff. PADE was already park adjusted for
each team’s entire schedule, weighted by the number of games they played in
each park, so again, there’s no reason to halve the park factor.

Before we get to the final numbers, one more note should be made. As
mentioned last time, the BasePIDE range is significantly larger than the
BasePADE range. The likely explanation for this is that teams play behind a
unique pitching staff (save for trades) all season long while they play in
many of the same parks. Sharing the same venues tends to keep the range
tighter because extreme parks have only half the effect of extreme pitching
staffs. Therefore, our final metric will usually be altered more by
pitching staffs than by park factors. In the battle of the lame acronyms,
PIDE wins.

Finally, here is the end result, in a scale that should look similar to
the regular Defensive Efficiency charts:

Team                      TAD
Houston Astros          .7390
Philadelphia Phillies   .7235
Atlanta Braves          .7199
Montreal Expos          .7185
Cleveland Indians       .7168
Pittsburgh Pirates      .7162
San Francisco Giants    .7158
Anaheim Angels          .7158
Los Angeles Dodgers     .7140
Oakland Athletics       .7131
Kansas City Royals      .7130
St Louis Cardinals      .7125
Chicago White Sox       .7122
Detroit Tigers          .7108
Tampa Bay Devil Rays    .7107
Chicago Cubs            .7106
Minnesota Twins         .7101
Arizona Diamondbacks    .7092
Cincinnati Reds         .7061
San Diego Padres        .7060
Toronto Blue Jays       .7035
Florida Marlins         .7029
New York Mets           .7022
Seattle Mariners        .7019
Boston Red Sox          .7013
Colorado Rockies        .7011
Texas Rangers           .6989
Milwaukee Brewers       .6984
New York Yankees        .6961
Baltimore Orioles       .6837

The distance by which Houston outplayed the rest of the league in the
field is a little unsettling, especially considering Craig Biggio was
roaming center field, but that’s what the numbers say. The team that moved
the most from Bill James’ original Defensive Efficiency ratings was Seattle,
falling from tops in the league to the bottom third, the result of playing
in so many defense friendly parks and behind a very defense-friendly staff.
The secret to Seattle’s defensive success this season appears to be due to
their pitching and park more so than with other teams around the league.

Again, what exactly is TAD good for? TAD is a highly independent measure
of team defense, telling us how good the defense is rather than depending on
the pitching staff or the park to do the work for them. If you’re looking
for how a pitcher would do on a different team, it’s best to use PIDE,
removing only the pitching numbers from a defense, but leaving park factors
in place. Likewise, when determining how a defense would do in a new
stadium, PADE is a better measure because the pitching staff would remain
the same. However, if what your chasing is simply how good the team in the
field is compared to everyone else, then TAD is your metric of choice.

Thank you for reading

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