I am sticking a thread for those that want to post about a stat that they have learned about, or is a new stat that they find interesting.

Do your best to explain in complete, and be able to answer questions for the stat.

I learned about this stat a few years ago, but it's still useful, and really it is under utilized when discussing teams defenses, and how it might impact a pitcher.

Defensive efficiency.

You can find each teams defensive efficiency ratings by going to
then select seasons
2012 mlb
then under fielding, sort by DefEff

In 2012, league average was .691

This is very simply. The number of outs on balls in play that a team converted into outs.

This is subject to fluctuations by pitchers that give up stronger contact vs weaker contact.

But it's also a sign of how well a team plays defensively vs another.

An example is when someone says Justin Verlander had worse defense than Jered Weaver, thus the ERA differences

Well DefEff
League average is .691
Angels led baseball with a .708
Tigers were 5th to last with a .678

So there might be some truth to that accusation.

Anyway, additional tool to use to help find more information