Evaluating the defense of the Yankees’ potential shortstop targets

The New York Yankees will shop for a new shortstop this offseason. General manager Brian Cashman recently confirmed that Gleyber Torres will play second, so the organization will try to find a replacement in the upcoming weeks and months. This year’s free agent shortstop class is filled with talent, and the Yankees may try to bring one star, even though top prospects Anthony Volpe and Oswald Peraza aren’t too far from the majors.

While the Yanks often prioritize offense, they haven’t had a defensively solid starting shortstop in quite a while. Before Gleyber, Didi Gregorius manned the position, and Derek Jeter preceded Didi. Both Volpe and Peraza are reportedly good out there, but they may not be ready for the big time in 2022.

It might be a good idea for the Yankees to splash the cash and bring one of the top free agent shortstops: Carlos Correa, Corey Seager or Trevor Story. If the kids are ready by 2023, the Yankees would have a good problem on their hands, one that can be easily solved by moving the worst fielder to another position.

But how can the Yankees decide which shortstop to pursue, if that’s the route they decide to take? The trio is comparable offensively: Seager has a career 132 wRC+, Correa is at 128, and Story checks in at 112, dinged by the fact that he plays his home games at Coors Field. How about their defense, though?

Evaluating a fielder is tough, because there are several resources and a lot of confusion. We will examine the three players’ defensive numbers according to four metrics:

Fielding Runs Above Average, or FRAA, uses play-by-play data instead of zone-based fielding data. It’s Baseball Prospectus’ go-to defensive metric and couples the aforementioned play-by-play data “with adjustments made based on plays made, the expected numbers of plays per position, the handedness of the batter, the park, and base-out states.”

Ultimate Zone Rating, or UZR, also tries to quantify how many runs a fielder saves, using four components: Outfield Arm Runs (ARM), Double-Play Runs (DPR), Range Runs (RngR), and Error Runs (ErrR). Per FanGraphs, UZR is “a measure of the average amount of damage that batted ball would do and how often it is converted into an out, relative to average at the position.” For this exercise, we will use UZR/150, or UZR per 150 games.

Defensive Runs Saved, or DRS, tries to quantify how many runs a fielder, well, saved. It weighs errors, range, outfield arm and double-play ability. It’s similar to UZR, but the formula differs. MLB.com provides an excellent example to show how DRS is calculated: “a center fielder sprints to make a nice catch on a fly ball. Then, data from BIS (Baseball Info Solutions) tells us that similar fly balls get caught 60 percent of the time. That center fielder gains, essentially, 0.4 bonus points for difficulty. If he can’t make the play, he loses 0.6 points.”

Outs Above Average, or OAA, is based on range and also tries to determine how many outs a player has saved. It’s calculated differently for outfielders and infielders, so for the purposes of this article, let’s focus on the latter. It considers these factors: How far the fielder has to go to reach the ball (“the intercept point”), how much time he has to get there, how far he then is from the base the runner is heading to, and, on force plays, how fast the batter is, on average.

According to the folks at Baseball Prospectus, FRAA is better for outfielders and OAA is better for infielders. Some prefer DRS for infielders, though. Here is how our players did in the comparison in 2021:

Carlos Correa seems like the best defensive shortstop of the trio, with some difference. Just about every fielding metric loves him: he ranked in the 97^th percentile in OAA, he is athletic, has fluid movements, and a very good arm. The 21 DRS were especially impressive, and at 27, he should be able to remain a good fielder for at least half of his next contract, if not more.

Trevor Story has an odd defensive profile. OAA thinks he had an awful 2021 (in the 4^th percentile) and FRAA thinks he was bad, too. However, he had a solid DRS and a positive UZR/150. The eye test suggests he is a solid fielder, though maybe not on Correa’s level right now. He rates much better than our third player in the exercise.

Every defensive metric used in this evaluation (there are plenty more) thinks Corey Seager is a lousy defender at shortstop. It’s also difficult to get a hold of what people think about his glove, because it usually ranges between average and one of the worst in the league. But it’s fair to point out he had 4 OAA in 2019 and 1 in 2020. He has the potential to be decent.

Correa is the likeliest player to stay at shortstop for the long term, and Seager the least likely. The latter’s arm isn’t a big enough strength to suggest he could be a top third baseman, in case he needs to move. But as long as he can keep mashing and hold down the fort for one or two seasons at short, the Yankees will probably live with these issues in the hypothetical case he signs.

If you were wondering about Javier Baez, the other accomplished free agent shortstop in this year’s class, he had a 1.3 FRAA, 3 DRS, a -0.1 UZR/150, and 4 OAA: 1 at shortstop, and 3 at second base in 2021. As a fun fact, he had a 31 OAA season in 2019.

It will be fascinating to see which shortstop the Yankees decide to pursue during this offseason, and how much will they consider defense in the equation. It should be a variable they take into account, given the presence of Volpe and Peraza could mean changing things around defensively in the future.