You saw this post’s headline before you read this sentence. The headline’s a question, so you probably answered it. I’m guessing your answer is, “probably not, no.” Or maybe it’s, “well we have no way of possibly knowing.” Or maybe it’s both. And that’s perfectly fair — we don’t have any way of possibly knowing for sure, and there was a lot of baseball before 2013 Andrelton Simmons. But if you’re reading this post anyway, it means you’re curious. And curiosity requires an open mind. You’re willing to consider the possibility that Simmons is having the best defensive season ever, and that might say enough on its own.

The other day, Jose Iglesias did something amazing, and I wrote about it. I don’t think it’s the greatest defensive play by a shortstop I’ve ever seen, but a full write-up felt appropriate, given Iglesias’ reputation and given his importance to a contending Tigers team with the rest of the Tigers’ defensive infield. Eventually, it had to be noted that no matter how good we think Iglesias might be, there’s already an Andrelton Simmons. Iglesias, this year, has been a good shortstop for 318 innings. Simmons has been a good shortstop for more than a thousand. Iglesias is going to be hard-pressed to emerge as the best defensive shortstop in baseball, because Simmons pushes sensibility to the extremes, and with his 2013 in particular, we have to wonder: how does this stack up? Where does this season fit in all-time?

We begin with the knowledge that we can’t have a good answer. Defensive stats, now, in their current and most advanced form, are hotly disputed and somewhat unreliable. Defensive stats before now were even worse, and people in the 1920s probably didn’t dream that people in the 21st Century would much care about the defensive performance of Frankie Frisch. I reject the notion that early baseball defensive measurements are useless. I accept the notion that the error bars are massive. This is more of just an exercise for fun, for the sake of fun. Let’s just ask the question: is Andrelton Simmons having the best defensive season ever? What does the evidence say, even if it isn’t great?

Probably not, no

We have UZR information going back to 2002, so we might as well use it. We can look at qualified individual single seasons, and right now 2013 Simmons has a UZR of +20.6, and a UZR/150 of +26.6. Those numbers are outstanding! But 2010 Brett Gardner had a UZR/150 of +31.5. In 2007, Alfonso Soriano had a raw UZR of +33.2. If you’re worried about skill positions, then you have to look at 2009 Franklin Gutierrez. Just this year, Simmons has a slightly lower UZR than Manny Machado, although Machado plays an easier position. The take-home: Simmons probably won’t finish the year with the highest UZR since it was first tracked. Even after you include positional adjustments, it gets messy at the top. Simmons looks outstanding, but he’s not the clear No. 1, even since 2002.

Well, maybe?

We have DRS information going back to 2003, so we might as well use it. Here are the top 12 recent seasons in Defensive Runs Saved:

At the top, we find Simmons one back, in a tie. It’s also just the middle of August, and Simmons trails Everett by nearly 300 innings. As the season goes on, it stands to reason Simmons will only add value, separating himself from the rest. So there’s an argument to be made that Simmons is having the best defensive season since 2003.

And then we turn to Baseball-Reference and Total Zone to find some longer-term historical data. Here’s a link where you can read about Total Zone, and that’s the best we’ll be able to do. Different eras are treated differently, depending on the available data, but the ideas are the same, and let’s just look at the all-time top 10, while we’re here:

(Update: it’s come to my attention Baseball-Reference uses Total Zone pre-2003, and DRS since 2003.)

Simmons shows up on the list, five from the top, and again, it’s the middle of August, meaning Simmons should add to his number between now and the playoffs. He’s on pace to finish at +46, and he was extraordinary by the same stat a year ago. If you sort everyone by Total Zone per 150 games, we find Simmons highest all-time, a few runs ahead of 2009 Jack Wilson among shortstops. This, right here, is the argument for Simmons having the best defensive season ever. We don’t have quality all-time defensive data, but the data we do have says Simmons is unbelievable. It’s not literally meaningless. By definition, there is an argument for Simmons’ 2013 defensive season being historically relevant.

So how is this happening?

If you mean statistically, I don’t feel like getting into the calculations. If you’re just wondering what makes Simmons so good, that part I can handle. Eno talked to Simmons in May, and one things Simmons does is position himself pretty deep to take advantage of his incredible arm:

That arm strength allows Simmons to position himself deeper in the hole than many shortstops, but it’s not the arm strength alone. “Sometimes I feel like I play more in the hole because I feel like going to my left side, I still have a good chance to get that guy,” Simmons said, adding that since he is comfortable there because he has his “arm protecting that hole,” he can still make the play from his deeper position.

According to the 2012 Fan Scouting Report, Simmons was tied with Yadier Molina and Bryce Harper for having the strongest arm in baseball. Aside from having a great arm, Simmons doesn’t screw up plays he shouldn’t screw up. Friends at Baseball Info Solutions passed along some data, showing shortstop performance on “routine plays,” those being plays the average shortstop makes at least 50% of the time. This year, Simmons has converted nearly 96% of those plays. Next-best is Cliff Pennington, at 93%. Then there’s Pete Kozma, right above 91%. It isn’t just making plays shortstops don’t make — it’s making all the plays they do.

But, there are those plays shortstop don’t make. Below, some of 2013 Simmons’ most impactful defensive plays, with regard to Defensive Runs Saved. Some of them might not look all that difficult. That’s not the play — that’s Simmons.

All together, those five plays were worth +3.2 runs in plus/minus. You can just trust me when I say there’s a lot more where these came from.

Right now, Jose Iglesias is good, but Andrelton Simmons has to be considered the best defensive shortstop in baseball. In fact, there’s a not-completely-stupid argument to be made that 2013 Andrelton Simmons is having the best defensive season ever, through baseball history. We could never know that for sure, because even today, we measure defense like we measure soup temperature with our fingers. There’s no further the discussion can go, not with information that’s publicly available. But there’s been a whole lot of baseball over the years. Within that vast landscape, Andrelton Simmons is making his visible mark.