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Why the Rays will make Matt Duffy - an elite 3rd baseman - their new shortstop

Analyzing the “win-now” part of the Matt Moore trade

Toronto Blue Jays v San Francisco Giants Photo by Ezra Shaw/Getty Images

The Rays just traded starting pitcher Matt Moore to the San Francisco Giants, and got back a toolsy young shortstop Lucius Fox, a projectable young pitcher Michael Santos, and Matt Duffy, a third baseman who put up five wins above replacement last year (that’s an all-star level), and who is under team control for four more years after this one.

Which is odd, because third base is, you know, one of those positions on the Rays that’s already sort of set. There’s this guy named Evan Longoria. Maybe you’ve heard of him.

So what’s the deal?

Sure Matt Duffy is a good baseball player, but why would Silverman and Co. bring him in if he’s going to be blocked? Is Longoria about to be traded?

No. Not yet.

It comes down to the belief — which this Rays front office clearly has — that a player can be moved around the diamond without dramatically changing his value.

Matt Duffy is a very good defensive third baseman. So they’re going to move him up the spectrum.

The Defensive Spectrum

At the core of this move is the idea that the different positions on the baseball diamond (or at least on the infield) aren’t all that different. While there are somewhat different movements and athletic requirements, fielding a grounder at third base is the same basic skill as fielding a grounder at shortstop.

And sometimes players do move between positions. Years ago, Tom Tango used those players who swapped positions to create the defensive spectrum most-commonly cited. It holds that shortstop is about five runs (over the course of a season) more difficult than third base. More recently, Jeff Zimmerman reevaluated that spectrum and came up with a smaller difference of three runs.

And there’s reason to believe that the transition would be relatively easy for Duffy. For one, he came out of the minors as a shortstop but transitioned to third when he was blocked there in San Francisco by Brandon Crawford, and he’s even played shortstop at the major league level before (51 innings in 2014, 15 innings in 2015). And for two, he’s a very good defensive third baseman. He has runs above average to spare.

Over 1150.1 innings at third base in 2015, UZR ranked Duffy as 10.6 runs above average, with 7.7 of those being attributed to range. Over 589 innings this season, it has him as 7.5 runs above average, with 5.5 coming via range. Defensive Runs Saved agrees with UZR, rating him as +12 last season, and +11 in limited time this season.

Point is, the man is slick.

Here he is making a nice stop while playing pulled in on the infield.

And here he is, shifted over almost to a shortstop position, making a play in the hole.

How about one more? Here he reacts to a deflected ball and barehands it for the out.

Moving Miller

Brad Miller’s offense has been everything Rays fans hoped for this season, but his performance as an everyday shortstop has been something less than they might have expected. Frankly, he’s been terrible.

The eye test tells us that he’s lacked range, and the stats stamp an exclamation mark on it, with UZR setting him at 11.5 runs below average (a whopping -30.7 per 150 games!) and DRS giving him an even worse -14.

Miller has never been this bad before, so there’s reason to doubt the extreme nature of those numbers, or at least to think he’ll improve, given more time. But there’s also plenty of reason to think that he’s not the answer as an everyday shortstop.

Brad Miller will stay in the lineup, but he’ll do it while transitioning to other spots on the field.


In short, the Rays pursued an elite defender over several seasons until they acquired him, and will deploy him at short stop at the expense of Brad Miller, who moves into a utility role.

And with that, your new Rays offense looks like this:

C1 - Curt Casali

1B/OF - Brad Miller
2B - Logan Forsythe
SS - Matt Duffy
3B - Evan Longoria

LF - Desmond Jennings
CF - Kevin Kiermaier
RF - Steven Souza Jr.
DH - Corey Dickerson

C2 - Luke Maile
UT - Tim Beckham
UT - Nick Franklin
UT - Taylor Motter

1B - Logan Morrison (DL)
OF - Oswaldo Arcia (DL)
OF - Mikie Mahtook (DL)

Maybe the player who should be most unhappy with the acquisition of another infielder is Tim Beckham, as Brad Miller supplants him as the go-to utility infielder.

Beckham has done a decent job this season with limited playing time, hitting at a league average level while giving average defense at shortstop, second, and third base.

But now Beckham is solidly behind Longoria, Logan Forsythe, Matt Duffy, and Brad Miller on the infielder totem pole, and playing time may get even more difficult to find as prospect Taylor Motter will likely push him out of the way on the depth chart next year as the 25th man.

These are difficult decisions, but ones that a great player like Matt Duffy forces an organization to make. Overall it’s a good problem to have.