Evaluating goalkeepers: Save Percentage vs Goals Against Average

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It’s nice to see MLS goalkeepers starting to pick it up. After a rough first couple months, we have finally compiled enough saves to have an honest Save of the Week competition.

So because of the sudden upswing in production, now is a great time to take a look at some stats instead of walking through every goalkeeper’s worse game this season. This month, we’re going to take a look at the stats Goals Against Average and Save Percentage to find out which one is worse. Or perhaps which stat is better, if you’re more optimistically inclined. It’s no secret that both stats are rather useless when gauging goalkeepers. There’s a reason why no one is bragging about being in the top ten GAA: it’s not that stellar of a group to be in. Sure we’ve got some of the all-time greats in there, but… Josh Saunders and Bouna Coundoul are in the list? Jimmy Nielsen is not only number one but he’s significantly ahead of his peers. That seems incorrect.

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A Visual Look At Shots On Target

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This is part of my efforts to try to come up with a zone rating of sorts for goal keepers. The problem I'm running into at the moment is trying to find visual information for shots against. If I want to know how good Dan Kennedy was preventing goals against Columbus in week 1, I have to go to Columbus' page on Squawka and narrow the shot data to that specific game. Basically, It just boils down to more time digging than I initially planned to devote. Quickly, here is a visual graphic that I made with the help of Excel. I know it's not really pretty, but it delivers the data in the manner in which I needed it without getting caught up on eccentric details, details with which I often spend too much time meddling. Shots+Goals and visuals

There isn't a lot that this immediately tells you, of course. It's more of a jumping off point to start comparing data once it is collected. That's where the next effort is going to be headed. Who are the teams that are above league average and below league average? Are they bleeding low percentage goals, or are they being beat in an unusual zone? This information, while still miles from being complete, moves us in the right direction of knowing more about shots and goals than what we did previously.

You'll notice that I also included shots that are wide but still close to the post. I'm curious as to whether these shots numbers become inflated when playing teams with "better keepers". Unfortunately we need to define what better is. Better than what, exactly? I'm not sure. Again, parameters haven't been set, and data sets are still being gathered.

This is a fun exercise and one that should, if nothing else, provide us with some excellent insight to teams and their seasons at this point.

ASA Podcast XVIII: The One Where We Discuss Defense Influencing Shots

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Family in town, waiting out this baby and being home doing nothing sure has made me lazy. So lazy that I really didn't get around to editing this and putting it together until last night. My apologies for the late posting. This week we discuss the USMNT and their romp in eastern Europe, a bit about Montreal and Omar Gonzalez. Then we transition to some discussion about whether goal keepers can influence shots on target. It's all some interesting stuff with a lot of giggling by me because I coined a new nickname for Drew.

 

[audio http://americansocceranalysis.files.wordpress.com/2013/08/asa-episode-xviii.mp3]