Just how good is this Galaxy defense?

The LA Galaxy's defense has been rock solid this year, letting in under a goal a game.  What's more, they've managed to accomplish this feet by giving consistent starting minutes to a center-back in Daniel Steres who is making the jump from USL to MLS quality offenses.

Of course, I don't want to heap too much praise on Steres as his poor clearance against Colorado, missed mark against Houston, and penalty against Real Salt Lake, all lead to goals, (43% of the goals the Galaxy have conceded), but, by in large, this new defensive unit that Bruce Arena has put together has stepped up beautifully and played a large role in the Galaxy's success thus far.

But how good is this defense really performing? Through 6 games (the data has yet to come in on the RSL game), the Galaxy are currently averaging 0.575 expected goals against per 90 minutes (xGA p90). For those not familiar with soccer analytics, this basically means that if you take the average scoring  rates (based on shot type and location, among other things) of the shots the Galaxy are allowing, they are only giving up a little over a half a goal a game in terms of chances.

How good is that number? For perspective, here are the top 5 lowest xGA p90 averages from 2011-2015.

As you can see, if the Galaxy were to finish the season today, it would smash the record by a huge margin. But is this Galaxy defense really this historically good?

With the sample size being so small, drawing any kind of conclusion is impossible at this time, however, there are a few things to point out in the data we currently have which can explain the Galaxy's current mind blowing numbers and help put them into perspective.

Strength of opposition offense

The first thing to consider is strength of opponents.  If we look at expected goals for per 90 (xGF p90), which is how many expected goals each team's offense is creating per game, we see that the Galaxy's opposition thus far falls below the league average.

What's more, that 1.366 is largely buoyed by DC United who are currently league leaders in the xGF category. Considering the Galaxy faced them on opening day, it's safe to assume their offense wasn't where it is now. If we remove them from our sample, the Galaxy opposition average drops to 1.233

So, while the Galaxy defense has done a good job of limiting the quality of the chances for opposition, they also have been facing teams who are below league average at creating quality chances.

Game State

But there is actually more going on here. Let's take a look at how the Galaxy fared against each opponents xGF average (as of 4/22), and consider the circumstances of each game.

The top offenses the Galaxy have faced so far are DC United, Vancouver,  Portland and Houston.

DC United Game- As we discussed, United's offensive numbers most likely do not reflect the quality of the offense that the Galaxy faced on opening day.

Vancouver Whitecaps game- The Galaxy played the majority of this game up a man, so Vancouver's offense was greatly weakened by this and didn't venture forward much.

Portland Timbers game- Portland was up a goal for a great deal of the game. When teams are up a goal, especially on the road, they tend to play more defensive. The Timbers also were without Nagbe after he went off injured, further reinforcing this tactic.

Houston Dynamo game- The Galaxy had a commanding lead for much of this game. As a team's chances of winning diminish, so too will their effort.

This leaves us with San Jose and Colorado, however, in the San Jose game, the Quakes were down a man for much of the game, and the Galaxy still managed to give up over 0.5 xG.

Once data has come in from the RSL game, things will be equally muddy when you consider that RSL are 15^th in the league in xGF p90, were completely demoralized by half time and were missing  Plata for the entire game and Martinez and Morales for most of it.

In other words, the question is still up in the air.

How good is this Galaxy defense?

As I stated before,there is not enough data to make any kind of conclusions thus far. What we can say is that the Galaxy's current 0.575 xGA p90 total is most likely inflated and likely to climb as the season goes on, however, this does not mean the galaxy defense is bad by any means. In fact, if the current inflation is anywhere under 0.425 xGA per 90 (which is a lot), then this Galaxy defense would fall into the 90^th percentile of all MLS defenses since 2011.

While it will probably be another 8-10 games before we have enough solid data to start drawing conclusions about the quality of this Galaxy defense, they are certainly one to watch going forward.

Update: The data from the RSL game is in and the Galaxy defense currently sits at 0.77xGA p90 as of 4/27