Welcome back to Stats All, Folks, our year-long look at the analytic side of baseball.

The previous editions have covered plenty of sabermetric stats for hitters and pitchers. But now let’s get a little crazy. Today we’re going to look at advanced metrics for fielders — specifically, Defensive Runs Saved (DRS).

Dan Connolly, for one, isn’t a fan of advanced defensive metrics. That’s why I’m sneaking in this story while he’s away on vacation. Shhh! Mum’s the word.

Why use Defensive Runs Saved?

Before we get to the specifics of what this stat entails, let’s think about why it can be more useful than conventional fielding stats.

When many people talk about defense, they cite errors and fielding percentage as their go-to stats. Unfortunately, those can be greatly flawed.

One issue is that errors are determined by an official scorer, so they tend to be subjective. One official scorer could rule a play as an error that another would call a base hit. Sometimes, players or teams will lobby for the official scorer’s ruling to be changed from a hit to an error (or vice versa) to benefit their hitter or pitcher.

Another major problem is that there are plenty of poor defensive plays that aren’t called errors. If a fielder has poor range or takes a bad route or is just too slow to get to a ball, he usually won’t be charged with an error, even though he failed to make a defensive play.

For example, think about if I were playing center field for a major league team. I have all the range of a potted plant. If anything were hit a few feet to my left, or right, or behind me, or in front of me, chances are I wouldn’t even get close enough to the ball to put a glove on it. It’s possible I might run around in circles like a frantic chicken.

Basically every ball hit in my direction would fall in untouched. Yet I would probably be charged with very few errors, despite my defensive incompetence, simply because I didn’t have a ball clank off my glove. That’s an extreme example, sure, but it exposes the underlying flaw with errors.

So let’s consider a different way to measure defense.

What is Defensive Runs Saved?

DRS is a stat devised by The Fielding Bible that attempts to paint a more comprehensive picture of a fielder’s ability. It’s a positive or negative number measuring how many runs a fielder has saved his team — or cost his team — with his defense.

It boils down to two main questions. First, how well (or poorly) does a fielder turn balls in play into outs? And secondly, how many runs would normally be expected to score on that play?

To determine this, whenever a ball is put into play, it is compared with all other balls in play in past seasons that had the same speed, location, elevation, etc. (That data comes from the analytics company Baseball Info Solutions.) Analysts look at how often that type of play would turn into an out rather than a base hit, and how many runs the offensive team would score if the fielder didn’t make the play.

So let’s go back to the earlier example of using poor, overwhelmed Paul Folkemer as a center fielder. As I ponder how I ever got into this predicament, a batter hits a fly ball to medium-deep center field. I stumble around and flail helplessly as the ball drops in for a double.

That’s a play that, historically, most center fielders would easily make. It’s also a play that, on average, is going to cost my team some runs, because putting a runner at second base is obviously worse than getting him out. So Defensive Runs Saved would deduct some points from my score for that misplay.

DRS also factors in different types of defensive plays, depending on a fielder’s position. For example, infielders are rated on their ability to field bunts and turn double plays, outfielders on their ability to throw out runners, and pitchers and catchers on how well they prevent stolen bases.

In general, a fielder with a DRS in the +10 to +15 range is well above average. A +5 mark is solid, while anything less than 0 is below average. A fielder with a -10 to -15 mark is really costing his team a lot of runs defensively.

Now, I’m contractually obligated by Dan to point out that Defensive Runs Saved has its share of drawbacks, too. For one thing, it doesn’t take into account defensive shifts or positioning. Imagine that a batter hits a routine grounder to where the third baseman would normally be positioned — except that the team is using a Chris Davis-type shift with the third baseman stationed near second. There’s no possible way he could make that play, through no fault of his own, but DRS would still give him demerits.

Also, DRS is unreliable in small samples. Don’t expect to learn anything by looking at one week or even a few months’ worth of DRS. One or two plays could greatly skew the numbers. In the same way, if Player A has a +3 DRS and Player B has a +1, that’s not definitive proof that Player A is the better fielder. There are many factors in play that could lead to discrepancies. DRS, like any stat, shouldn’t be considered a foolproof measurement.

The Orioles and Defensive Runs Saved

What does DRS tell us about the Orioles’ defense? Well, it’s not very kind. If DRS is to be believed, the Orioles’ defense has suffered a dramatic decline during the past three years.

In 2014, the Orioles’ defense ranked as the best in the AL, compiling a whopping +57 DRS. Every Oriole who played at least 500 innings at a position posted a positive DRS, led by shortstop J.J. Hardy and second baseman Jonathan Schoop at +10 apiece.

Since then, according to DRS, it’s been all downhill. In 2015, the Orioles dipped into a negative DRS (-7), ranking 11th. Despite Herculean efforts by third baseman Manny Machado (+14 DRS) and catcher Caleb Joseph (+9), the Orioles were hurt by poor defense at the outfield corners, particularly Gerardo Parra, who stumbled to a -7 DRS in two months with the club.

As for 2016, the Orioles fell further with a -25 DRS. Again, the club’s leader was Machado (+13), while first baseman Chris Davis (+8) also excelled. But the outfield was the Achilles’ heel, with the Orioles’ three most used outfielders — Hyun Soo Kim (-13), Mark Trumbo (-9) and even the normally reliable Adam Jones (-10) — posting the three worst marks on the team.

This year, based on DRS, the Orioles are off to another rough start defensively. Their -9 DRS ranks third-worst in the American League. As I mentioned, though, two months is too small of a sample size to make strong judgments.

Again, don’t take these numbers as gospel. But they’re interesting to consider. And they suggest that the Orioles’ recent reputation of being a strong defensive team may not be all that accurate.