This winter has been one of the weakest markets for middle infielders in recent memory. You remember the shortstop glut of recent years? Carlos Correa, Corey Seager, Francisco Lindor, Trevor Story, Xander Bogaerts… the list of players who either reached free agency or signed extensions to take them off the market went on and on. But this year, the pickings were slim. Depending on personal preference, the best second baseman or shortstop available was… Whit Merrifield? Isiah Kiner-Falefa? I would have said Amed Rosario, only the market clearly disagrees:

Infielder Amed Rosario and the Tampa Bay Rays are in agreement on a one-year, $1.5 million contract, sources tell ESPN. Rosario, 28, will bring a strong bat against left-handed pitching and should get at-bats at shortstop, second base and potentially corner-outfield spots.

— Jeff Passan (@JeffPassan) February 20, 2024

That’s a shockingly light deal for Rosario, at least in my head. I had him at the tail end of my Top 50 free agent rankings, and the crowd and I both penciled him in for a two-year deal worth $8 million per year. Instead, he’s getting less than a fifth of that AAV, and for only a year at that. This merits some investigation, both into why his market didn’t develop and why the Rays came calling in the end.

If you’re looking for a reason not to sign Rosario, it’s pretty easy to come up with a handful. The first one is fairly obvious. He just put up a season worth 0.2 WAR, which is about as disastrous as it sounds. The reason? His defense at shortstop was downright abysmal. DRS and OAA agree that he was one of the worst regular shortstops in baseball, 10 runs or so below average in an abbreviated run as Cleveland’s everyday option.

That’s putrid stuff, plain and simple. If you play shortstop that poorly, you probably shouldn’t play shortstop at all. The Dodgers clearly concurred; even with a clear need at the position, they relegated Rosario to second base duty after trading for him. But good news! He handled second base fairly well, so he can still play an up-the-middle defensive position, which gives his value a nice floor.

Back to the bad news: If you’re going to play acceptable second base defense, you can probably get away with being a league average bat. But Rosario wasn’t average — his 88 wRC+ wasn’t quite disastrous, but it’s the kind of line you can accept from a slick-fielding guy, not a defender who is average at best. An average hitter who plays average second base defense is a nice major leaguer. Downgrade either side to below average, though, and we’re talking about replacement level or thereabouts.

A little bit of everything went wrong for Rosario at the plate last year. He has never hit for a ton of power, but he hit for less than ever in 2023. His underlying numbers back that up; every permutation of his batted ball data says the same thing, that he was making impactful contact less frequently than before. In the past, he’d been able to offset that lack of pop by slashing and sprinting his way to a high BABIP. He didn’t do abysmally on that front in 2023, but even a .310 BABIP wasn’t enough to rescue his overall offensive value. The combination of a low walk rate, low power, and a merely acceptable batting average turned him into an offensive liability.

That’s always been the downside risk with Rosario, and that’s why he ended up with such a modest contract. If things don’t pan out, he’s not much better than someone you could pull up from Triple-A. But that’s now baked into the contract; even for the penny-pinching Rays, $1.5 million will hardly break the bank. That means that Tampa Bay can focus on the upside he might bring to the table, and that’s considerable.

Let’s start with one obvious limitation of Rosario’s that might work out in the team’s favor: He’s probably not an everyday player unless his offense improves significantly. Rosario has been an awful hitter against righties in his career, posting a .262/.296/.374 line, but he checks in at .298/.339/.467 against lefties, a huge improvement. Even if you regress that a long way back towards the mean, as befits someone who has faced lefties 948 times in his career, we’re looking at someone with somewhere between double and triple a league average platoon split. If you think Rosario is a 95 wRC+ hitter overall, that works out to something like a 91 wRC+ hitter against righties and 104 against lefties.

That’s a middling case, but you can imagine better scenarios than that. However good of a hitter you think Rosario is, the Rays could make him significantly better simply by putting him in more advantageous situations. And wouldn’t you know, that’s kind of their specialty. A quick look at their roster shows two easy places Rosario could work into the mix without eating at-bats against righties. He could form a pure platoon with Brandon Lowe, the incumbent second baseman and a lefty who has at times struggled against southpaws. He could also platoon with Jonathan Aranda, who we currently project as the DH.

Either of these roles will be inherently limited by the number of lefties the Rays face. Randy Arozarena got all the lefty looks he could handle last year, which came out to 138 plate appearances. Yandy Díaz got to 139. There are only so many plate appearances to go around against lefties because there are only so many lefty pitchers. Even the most platoon-happy righties end up facing mostly same-handed pitching because of the way that handedness works.

That’s the bad news. The good news is that 150 or so plate appearances against lefties goes a long way towards juicing up Rosario’s value. He’ll play plenty of games with righties starting thanks to Tampa Bay’s whirling configuration of bodies. Maybe Lowe will get a rest day at DH and let Rosario handle second. Maybe he’ll spell Jose Caballero at short, or cover a corner outfield in some weird flex operation. With his speed and ability to hit lefties, he’ll also provide late inning utility.

In some ways, the Rays seem like an obvious fit for Rosario’s talents. No one shuffles and reshuffles quite like they do, and no one else finds little edges for just the right players the same way. That extra juice matters a lot for players like Rosario, who projects as a below-average player if used in a “standard” way. By excising the spots where he’d be at a disadvantage, the Rays will likely get more per plate appearance out of Rosario than any other team in baseball might.

On the other hand, Rosario will probably get fewer total plate appearances with the Rays than he would anywhere else interested in signing him. That’s just part of how they operate, with few players on the 40-man roster getting anything approaching full playing time. The Rays don’t sign a lot of average regulars, because the value that those kinds of players provide is blunted by the lack of available playing time.

If Rosario signed for anything approaching what I was projecting, he never would have ended up on the Gulf Coast. The Rays simply don’t operate that way. But when his price tag dropped, he became far more attractive. When the league values a player this close to the minimum, using them as a part-time player makes good baseball and economic sense. It’s a reasonable deal for Rosario, too; if he wasn’t getting much money in 2024 regardless, there’s no better place to play than somewhere that will flatter his rate statistics in advance of a dip back into free agency next year.

There’s something else at play here, at least potentially. I can’t take much credit for this insight, but I also can’t pin down who said it first, because I picked it up over the course of reading a lot of our comment sections. Basically, teams are getting so good at developing Rosario-esque players internally that they’re being devalued in free agency. If you can generate an average-glove, slightly-below-average-bat second baseman from your farm system at will, there’s no reason to offer someone like Rosario a market rate in free agency. The more teams churn out 1-2 WAR middle infielders, the less that group of players will be in demand.

It doesn’t pass cleanly up the line to more accomplished hitters, or at least it hasn’t yet. You might be able to generate 95% of Amed Rosario for a bargain rate, but the same can’t be said for Jose Altuve. But the middle class of up-the-middle defenders – yes, I said that on purpose – is feeling it in their wallets at the moment. There are knock-on effects worth considering, too. The old argument in favor of defensively versatile prospects who might struggle to hit at the major league level is that they could still become average middle infielders. Just look at literally Amed Rosario for an example of that. But if that kind of player isn’t worth so much on the open market anymore, if you can get those types of hitters more or less freely, then the calculus changes.

It’s funny to me that the Rays are the ones signing Rosario. For years, they’ve been the ones generating middle infield prospects to avoid hitting the free agent market for those players. But now the tables have turned, and they’re wisely changing with the times. Right now, there are enough so-so (relative to the best major leaguers) middle infielders that you can sign them for cheap. So naturally, the Rays are doing just that, and picking the ones who most fit their roster construction style to do so. Good work, Rays; the rest of baseball surely won’t be far behind on the same plan.

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