I’ve spent most of this season watching third basemen. I’m not entirely sure why. I’ve just found my eye drawn to the position. When I’m at a game, I watch the way they set up, the way they move before and during their pitcher’s windup, the way they communicate with their fellow infielders, and the way they address batted balls of all kinds that come near them. It’s been an informative experience.

To share it in a way that’s not overwhelmingly wonky, I’m going to distill it into a subjective ranking of all 30 starting third basemen defensively (repeat: only defensively). Please don’t take this as a capitulation to convention; I just want to talk about the vastly variable styles and body types and skill sets that can make up a big-league hot cornerman, without losing us all in 2,000 words of unworthy Angell mimicry. This is a fun, perhaps conversation-starting access point to a subject I think can be really complex and fascinating.

Let’s start with the worst today and then make our way to the best tomorrow.

30. Nick Castellanos, Detroit Tigers — I spent the summer re-teaching myself to run, because Castellanos said he did that over the winter of 2016-2017 and then actually added substantially to his sprint speed this year. I was dubious of the idea, but it turned out that I really was able to make myself faster by changing the way I thought about the moment of impact between my foot and the ground. I therefore believe that Castellanos did the same, and is genuinely a better pure athlete than we used to think he was.

That said, he’s an atrocious third baseman. He doesn’t use his speed well at the position. His lateral movements are robotic and his hands are stone. There was a reason why Detroit was willing to make this kid wait while Miguel Cabrera manned third base just a few years ago, and now that he’s learned to run and can access his full speed potential, they ought to move him back to the outfield for good.

29. Pablo Sandoval, San Francisco Giants — This should be a joke, and almost actually is one. Simply because he better handles what comes right at him, though, Sandoval might be a better third baseman than Castellanos. (It’s still a joke of another kind that the Giants have essentially made him their regular at the position, even accounting for the lack of obvious alternatives.)

28. Maikel Franco, Philadelphia Phillies — Every now and then, Franco will handle a blistering one-hopper with surprising aplomb, and then show off both a quick release and a strong arm. (One trap people fall into, when evaluating third basemen in the minors and even in their early years in the majors, is to overly praise their arms. Anyone who wants to play even an inning or two in the majors at third base needs a good arm. A guy, like Franco, with a good arm is only meeting the minimum requirement.) Much of fielding excellence lies in consistency, though, and Franco glaringly lacks it. He makes mental mistakes, doesn’t get down and field balls to his right cleanly, and can be caught either flat-footed or otherwise unprepared, costing him chances to get to balls that should be within his range, based solely on his tools.

27. Jake Lamb, Arizona Diamondbacks — There’s just nothing Lamb does well enough to be an average defensive third baseman. Like Franco, he has the arm to get an out one might not have expected now and then, but he lacks even Franco’s quick-twitch skills. He’s a better runner, and will keep his feet moving enough to make a play if a ball is hit slowly enough, and he plays quite deep, giving himself time to make up for relatively slow reflexes (while costing him something on dribblers, of course).

26. Luis Valbuena, Los Angeles Angels — For a short guy who doesn’t qualify as fat (although "stocky" would be fair), Valbuena is just unbelievably slow. His legs are heavy and they don’t even move well in conjunction with his upper half when he’s trying to make a play to either side. Valbuena’s such a bad defensive third baseman that even the Angels, who are often a bat or two short of a credible AL lineup, have to run Cliff Pennington out there on a part-time basis. To his credit, though, Valbuena has decent hands and a quick exchange from glove to throwing arm.

25. Cory Spangenberg, San Diego Padres — This will become a theme, but here is the first place where I view it as a worthwhile thing to say out loud. Many third basemen (and many players at a few other spots on the diamond) play there because it’s the most valuable defensive position at which they’re viable, and because their offensive and baserunning value more than offset whatever damage they might do on defense. That’s the case with Spangenberg.

It’s not just anyone who can pick up a glove and acquit themselves at third base in MLB, and while Spangenberg is quite poor there, he’s among those who can at least play the position. He’s also a good runner and about a league-average hitter, and a left-handed bat, too. He was drafted as a second baseman, but didn’t have the light feet for that job at this level. He doesn’t really have the arm for third, but he can cover enough ground and do enough to pad the other side of the ledger to make playing him worth manager Andy Green’s trouble.

24. Matt Davidson, Chicago White Sox — Look, if the White Sox hadn’t traded their starting third baseman at the deadline, Matt Davidson wouldn’t even be playing third base in the majors. Starting from there, it’s almost impressive that he’s merely bad, and not godawful. He’s a big guy (6-foot-3, 230 pounds, and that’s just what they list), but uses his size well: he plays shallow. By doing that, he gives balls hit toward his slice of the infield pie less time to make their way far to either side of him, without going foul or being the shortstop’s problem. He’s hardly the most notable or successful case study in this (though he might be the most extreme one), and we’ll get deeper into the concept later, but for now, know that Davidson survives at third only by changing angles and being ready to handle rockets.

23. Rafael Devers, Boston Red Sox — At 20, Devers is a terrific athlete, which is good because it’s the only reason he’s even made it this far at third base. He’s a tentative fielder, afraid to let a hard-hit ball carry him fluidly into quick actions and release, uncomfortable charging the ball and often caught in between on sharply hit grounders to his left. His arm is strong but not accurate, largely because he has so much trouble with the internal clock that should help him make throws in a natural rhythm. The good news, of course, is that his sheer athleticism has gotten him this far, and now he’ll have a couple years to learn the feel for the position he’ll need in order to play it well once his knees lose a bit of their spring.

22. Derek Dietrich, Miami Marlins — The Marlins have essentially replaced Dietrich with rookie Brian Anderson. It’s an understandable move. While Dietrich (a college shortstop, because who wasn’t?) plays low to the ground and handles the ball well, he’s thickly built, shapes his game around power, and lacks mobility. He’s a hair better than Spangenberg or Valbuena in the field, but no better at the plate, so he’s a fringe starter.

21. Mike Moustakas, Kansas City Royals — Trusting his spitfire arm (yes, his is strong enough to count as a weapon even when the big-league standard for arm strength is in effect), Moustakas plays deep and shades toward the line. He doesn’t move well, though, and it limits his overall value. Anything he gets to, he can turn into an out, because of the combination of his soft hands and that arm. He just lacks the range of a good third baseman.

20. Wilmer Flores, New York Mets — Like so many guys who sign at 16 as shortstops, Flores was never actually going to be one. It was clear before he was 18 that he was also going to be stretched at second or third base. There’s nothing at which he’s abysmal, but there’s also nothing at which he’s above average. He’s a guy with a first baseman’s body, but he never developed offensively to the point where any team could credibly call him their regular first baseman. Thus, he’s found his way to third, where his lack of athleticism is less galling than it is when he’s asked to play up the middle (it still happens, because the Mets gonna Met), and where his hands are good enough to handle the routine stuff.

19. Josh Donaldson, Toronto Blue Jays — I don’t want to generalize too much from an isolated case, not least because there are a number of counterexamples further up the list, but it’s worth noting that some third basemen age very rapidly as they reach their mid-30s. I run a query on Baseball Savant with some frequency, just to see where guys position themselves. I filter for situations where a right-handed batter is at the plate and the bases are empty, and I sort by average starting distance. It doesn’t perfectly capture anything, of course, but it’s a general guidepost.

In 2016, Donaldson played at an average depth of 116 feet in those situations, among the deepest in the game. This year, he’s down to 113 feet, close to the median (for guys with a decent amount of playing time). He’s playing a step shallower because, from his heel to his shoulder, he’s just not quite the same player. You can see in his setup, in the angles he takes on balls, and in the way he tries to set his body when he knows he’s going to need to make a quick and strong throw, that he’s not the Gold Glove-caliber defender the Blue Jays had even a year or two ago. He’s still not bad, but he’s fallen from well above average to below average, and unless he’s just a whole lot healthier next year, that change seems unlikely to reverse itself.

18. Rio Ruiz, Atlanta Braves — There’s not a whole lot on which to go where Ruiz is concerned. He’s had a few stints in the majors by now, but not anything that conclusively confirms or rebuts the industry line on his glove when he arrived. That consensus was that, while he’s somewhat limited by his size and lack of fast-twitch explosiveness, he has a fine arm, and has massively increased his concentration and consistency at the position. He reminds me a little of Aramis Ramirez—another two-sport athlete (Ramirez’s first love was basketball; Ruiz was almost a college football player) whose legs got a little thick while he was still young. Ramirez worked hard on his defense when he was first breaking in, and became serviceable, though his sheer physicality still held him back. In limited looks, Ruiz has the same vibe. (Now, if only he hit like Ramirez did.)

17. Alex Bregman, Houston Astros — If Carlos Correa and Jose Altuve stay healthy and Bregman stays an Astro, third base is his semi-permanent defensive home. If that’s the case, he’ll eventually be very good at it. His athleticism is sufficient. He reads and manages hops well. He can throw comfortably and accurately from myriad angles. Right now, though, he’s still developing a feel for the rhythm of third base, and for coming straight in on the ball, and for the throws required of him there.

16. Travis Shaw, Milwaukee Brewers — It’s still staggering that Boston gave up Shaw to get Tyler Thornburg. Sure, he’d been vocal about his (well-founded) displeasure with being denied an opportunity to play consistently for the Red Sox, and the naivete of the notion that Sandoval would recover his form at Shaw’s position was not yet obvious. But the clear alternative to trading him was to simply keep him, work through the mental roadblocks to his success in part-time roles, and await the inevitable moment when he’d have a clear path to playing time.

Anyway, Shaw plays extremely deep at third, allowing himself a little extra time to get moving on hard-hit grounders. He lacks range, because he just isn’t quick enough not to, but the balls within a step or two either way always seem to turn into outs using his strategy. It helps that he trusts his arm, and that comes into play when he’s charging bunts and weakly hit balls, too. He makes the easy plays, and just a few of the tough ones.

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To read Part 2, featuring the 15 best third basemen, click here.