The all-important annual event has come, and the offseason can now begin in earnest: Seattle Mariners GM Jerry Dipoto has finalized a trade with the Tampa Bay Rays.

The Rays are sending centerfielder Mallex Smith to the Mariners in exchange for centerfielder Guillermo Heredia and catcher Mike Zunino. Each club has thrown in a minor-league player: outfielder Jake Fraley goes to Seattle and left-handed pitcher Michael Plassmeyer to Tampa, though neither is a particularly notable prospect. If Smith to Seattle sounds familiar—it’s happened before, however briefly. Dipoto acquired Smith for all of two hours in January 2017, when he picked him up from the Atlanta Braves in exchange for Luiz Gohara. Almost immediately, he flipped the outfielder to Tampa Bay, for Drew Smyly. This time, though, it seems that the centerfielder is there to stay. So what does that mean?

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For Seattle, it looks like the start of the roster makeover that was rumored earlier this week. But taken in that capacity, it should be pretty encouraging for any fans who were nervous about the prospect of a teardown. This doesn’t seem so much like rebuilding as simply retooling. In the outfield, it brings the club a clear upgrade in Smith, whose defense is far better (14 defensive runs saved above average in the past three years) compared to -1 for Heredia. A big part of that skill comes from his speed, which makes him valuable on the bases, too. With 40 stolen bases in 2018, he ranked second in the American League, on an average sprint speed that put him in MLB’s 98th percentile.

The Smith-Heredia comparison gets more interesting when it comes to measuring the two outfielders at the plate. In two full seasons of big-league play, Heredia has been consistent. He makes a lot of contact (85.6% of his swings), without a lot of power, which has left him as decidedly below average hitter, on a career 83 OPS+. Smith, meanwhile, took a big step forward this year. In his first two partial seasons in the major leagues, his offensive output had been, well, right around Heredia’s: 85 OPS+. In 2018, his first full season at the big-league level, he looked better in just about every way. He reduced his strikeouts, made harder contact, and learned to hit a curveball. A 115 OPS+ was the result—the next question, though, is whether or not it’s sustainable. His true talent at the plate is likely somewhere in the middle, but either way, his defensive ability is more than enough to make him the stronger player here. And on the contract front, Smith and Heredia each have four years of team control remaining, with almost exactly the same amount of service time (literally—Smith has appeared in 294 games to Heredia’s 293).

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But the centerfielder swap is, of course, just one piece of the puzzle. Heading into the offseason, Tampa Bay looked like it could certainly make a move at catcher, with next year’s starter projected to be Michael Perez, a rookie who’d long lost his prospect shine. Zunino provides a clear improvement. He’s a player who would have been easy to dismiss, say, a decade ago—a catcher who strikes out in more than a third of his plate appearances and has struggled to hit .200. Now, of course, there’s enough information out there to offer a much different read on his value. Zunino’s a capable defender, and he’s a particularly strong pitch-framer. And at the plate, he’s much more valuable than is suggested by his career average of .207. With 20 home runs in three of the last five seasons, he’s developed into a solidly above-average hitter. After particularly strong showings in 2016 and 2017, he struggled with the bat in 2018; even then, he was still roughly an average hitter for a catcher. Zunino marks a clear upgrade at catcher for the Rays, and, if there’s no further move coming here for the Mariners, his loss will mean a clear downgrade at the position for them. Their in-house replacement is likely David Freitas, who exceeded his rookie limits this past season at age 29—which tells you about all you need to know for what to expect from him.

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The Rays and Mariners are in tough divisions. Each is behind two separate teams that won 97 or more games in 2018, which puts each in a difficult spot; they’re close to serious contention, but not close enough to be sure of it. But they’re going with different strategies here to approach their different constraints. The Mariners, with their heavy payroll commitments down the line, seem to be trying to unload a chunk of their roster without getting decidedly worse. The Rays, without any demonstrated interest in heavy payroll commitments to anyone, seem to be trying to get better without getting expensive. This deal likely doesn’t move the needle too dramatically for either club—a better centerfielder for Seattle, at the cost of a better catcher for Tampa Bay—but it does appear to fit both of those strategies, and it might offer a clue as to how their respective winters might look.