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Tracking The Safeco Effect

I'm so glad that our team finally does this
I'm so glad that our team finally does this

You'll remember that earlier this very year, Safeco Field was the source of much consternation. Perhaps that isn't accurate; perhaps it's more accurate to say that the Mariners were the source of much consternation, and it seemed like Safeco had a little something to do with it. We used to joke about there existing the Home Mariners and the Road Mariners, and we were only interested in watching the Road Mariners. They were only part jokes.

I figured it might be interesting to look at how the Safeco numbers have changed over time, if they've changed at all. I went into this not knowing what I might find and I'm still not entirely sure what to make of the results, but I'll publish them anyway because I'm pretty sure that's what science is. Used to be that Safeco was just slaughtering offense, skinning it, hanging it from a tree, and collecting the drippings for broth. Safeco still doing that? Statistics!

There have been 61 games played at Safeco so far. I decided to split them into groups of 20, with the most recent group getting the extra game. Assigning the extra game to the most recent group is arbitrary, but splitting into groups of 20 is also arbitrary, and this whole thing is kind of arbitrary based on the definition of "arbitrary." We're going to be looking at the core rate stats for both the hitters and the pitchers, which means for the Mariners' hitters and for the opponents' hitters.

This is just a paragraph of empty words to make sure the formatting in the post works well around the picture over there. I don't want the picture to interfere with the tables so I have to make sure that the tables are pasted below the picture, horizontally. Let's see if I've accomplished that. Looks like...yes! Okay, that's the end of this paragraph, I hope you enjoyed it. I've written a lot of pointless filler paragraphs but I've only been open about this one.

Now for the tables:

First 20 0.197 0.280 0.313 0.241 0.115
Next 20 0.199 0.273 0.274 0.246 0.076
Last 21 0.245 0.309 0.358 0.287 0.113
Overall 0.215 0.288 0.316 0.259 0.101

First 20 0.213 0.277 0.315 0.253 0.103
Next 20 0.231 0.292 0.352 0.272 0.121
Last 21 0.213 0.269 0.318 0.258 0.104
Overall 0.219 0.279 0.328 0.261 0.109

Obviously, there are two shortcomings here. One, the roster has changed since the beginning of the season, so we're not comparing exactly the same groups. When groups have changed, a proper comparison requires that you do something less simple than what I've done above, so, be aware of that. Secondly, nowhere have I included road numbers for easy reference. That's kind of the whole deal - offense has been down at Safeco, relative to what it's been on the road. Splitting into groups of 20ish games makes collecting "peer" road numbers tricky.

But still, we'll take a look, understanding thirdly that the sample sizes here are limited. The absolute biggest sample of all six is the last 21 for pitchers, spanning 743 plate appearances. That's the equivalent of one full season for Ichiro, and Ichiro's numbers would bounce back and forth.

In some ways, Safeco has gotten friendlier, and in other ways, it very much has not. Lately, the Mariners have posted a somewhat normal-looking home batting average on balls in play. Last night, at home, they hit three home runs, and they've hit seven home runs over the last four home games. But then they didn't hit at all in the Tampa Bay series before that, and the improvement over the last 21 games mostly just looks like BABIP correction. Power has only been present in spurts. The Mariners might not be a powerful team, but they have an isolated slugging percentage on the road of .156.

And nothing's changed with the pitchers, or, if you prefer, with the opponents. Again, because of the sample sizes we also can't correct for opponent identity, so that's an issue, but most recently opponents in Safeco have hit almost exactly like the season-average opponents in Safeco. Power's still down, batting average on balls in play's still down. Where the Mariners have peaked recently, opponents peaked in the middle group. Even there, they weren't good. Mariners pitchers have allowed a .608 OPS at home and a .774 OPS on the road. We're talking about the difference between a 2.92 ERA and a 4.52 ERA.

So the odd 2012 Safeco Effect doesn't look to be a thing of the past, just yet. The reason fewer people have been concerned with it is that the Mariners have been winning at Safeco. At one point, the Mariners' home record was 10-19. Now it's 31-30, and in Safeco the Mariners have won 13 of their last 14. It's their most successful 14-game stretch in Safeco history, and ultimately that's what people really care about. People might have their preferences for how they'd like to see their team win, but more than anything else, they just want to see their team win, and all the talk about Safeco was kind of misidentifying the problem. Safeco wasn't why the Mariners were losing. It might've been why the Mariners were losing the way they were, but as you don't need to be reminded, the ballpark plays the way the ballpark plays for everyone.

There's little reason to believe changing Safeco would markedly increase the Mariners' winning percentage at Safeco, relative to the winning percentage on the road. Changing Safeco would be about making things easier on the front office, and about making things easier on young hitters who might be having a difficult time, and who might be getting into bad habits. In a way, the winning is independent. It's great that the Mariners have been winning at home of late, and still it looks like Safeco could use a thorough offseason examination if the numbers don't shoot north down the final stretch. Something odd is afoot, or something normal is wearing an odd disguise.

Well now I feel like I've combined two points that should be separate points. This 2012 Safeco Effect needs to be figured out. I don't know if the team has a hypothesis, or several hypotheses, but it's beyond time for science. And even if there's nothing to the 2012 Safeco Effect, the organization still needs to think about whether Safeco should be adjusted, because there are bits of it that could probably stand to be more even. Bits of it that could be made more neutral, to the great relief of the hitters and general manager. In the event of changes, perhaps Jason Vargas should be kept in the dark.

Vargas: sayyyy that fence looks a little clo-
Zduriencik: /shoots tranquilizer dart
Kingston: /begins placing microchip in Vargas' brain