MLB Opening Day 2024: How different are all 30 teams compared to last season?

Which teams rebuilt over the winter, and which ones are running it back? Here's what the numbers say.

As we close the book on another offseason, there are many ways to assess what a team did to improve its roster over the winter. But rather than attempt to label teams as definitive winners or losers of hot stove season, with Opening Day on deck, I’m more curious about one simple question:

How different are the 30 MLB teams now, compared to the ones we watched in 2023?

Free-agent and trade activity throughout the winter months ensure that many of the game’s stars change teams before every season, but that’s not the only way rosters evolve. There’s natural turnover by way of injuries, player development and regression, and shuffles of the depth chart based on the preferences of the coaching staff or front office. Some teams decide to rebuild; others choose to run it back.

In turn, every new season features a fresh cast of characters performing in new settings across the league. For each fan base, the everyday contributors on the roster become the main characters of the season. Regardless of whether a team is good or bad, the connections with these players are a big part of the fan experience over the course of the summer and into the fall.

So instead of attempting to determine which teams improved the most since the 2023 season concluded, consider this an objective way to measure which fan bases will be tasked with learning the most new names and faces and which will be afforded the comfort of familiarity.

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The methodology was pretty straightforward: I looked at all the players who appeared in a game for every team in 2023 and tallied whether those players — and all the innings pitched or plate appearances they accounted for — were still in the organization entering 2024. For example, Logan Webb logged an MLB-leading 216 innings for the Giants in 2023, roughly 15% of the team’s collective innings total in the regular season. Webb is still with the Giants, so that 15% is returning. Conversely, the Giants’ leader in plate appearances — J.D. Davis, who came to the plate 546 times for San Francisco in 2023 — is now across the Bay playing for Oakland. That’s roughly 9% of the team’s plate appearances that is not returning.

While the spirit of this exercise is meant to convey which teams look the most similar to the previous year, it doesn't account for injuries. For example, while Sandy Alcantara’s 184 2/3 innings from last year will not be replicated in 2024 due to his recovery from Tommy John surgery, he still counts as part of Miami’s “returning” innings. On the flip side, there’s Oneil Cruz returning for the Pirates after missing most of last season following ankle surgery. Having come to the plate just 40 times in 2023, he accounts for only a tiny fraction of Pittsburgh’s “returning” plate appearances, but it’s safe to assume he’ll make up a much larger percentage of the Pirates’ playing time in 2024.

Beyond injuries, there’s no way to perfectly project the degree to which players will repeat their playing time from year to year. Sure, in the case of a guy such as Webb, we can count on a similar amount of innings, assuming he stays healthy. But circumstances change for many players from year to year, even if their threads remain the same. Still, we can identify the spots on the depth chart that appear largely unchanged from a year ago.

So which teams stand out? Let’s take a closer look.

Who rebuilt over the winter, and who is running it back? (Michael Wagstaffe/Yahoo Sports)
Who rebuilt over the winter, and who is running it back? (Michael Wagstaffe/Yahoo Sports) (Michael Wagstaffe/Yahoo Sports)

Philadelphia Phillies

On average, teams retained roughly 75% of their 2023 plate appearances and 67% of their innings pitched. The Phillies, meanwhile, represent by far the most extreme example of continuity, bringing back a whopping 94% of plate appearances — a number that was even higher before the late March trade of veteran outfielder Jake Cave to Colorado. Cave came to the plate 203 times for Philadelphia in 2023 before recording the final out of the Phillies’ NLCS defeat against Arizona. He also received by far the most playing time of anyone on last year’s Phillies who is no longer with the team.

On the mound, 86% of Philly’s 2023 innings are still in the organization, headlined by the crucial re-signing of Aaron Nola at the outset of the offseason. Craig Kimbrel is the only key contributor no longer in the fold.

Sure, we’ll sprinkle in a little Whit Merrifield and Spencer Turnbull in 2024, but for the most part, the Phillies are the Phillies, and we know them well. Perhaps most remarkable about Philadelphia occupying the top spot in these rate of return rankings is that following the recent extension of Zack Wheeler, nearly the entire team remains under contract through 2025, meaning this team could occupy a similar spot on this list a year from now. That said, it’s worth wondering if another disappointing October exit would spark a roster shake-up.

Houston Astros

The Astros are in a similar boat as Philadelphia: If it ain’t broke, why fix it? This is largely the same cast of characters who have been making annual trips to the ALCS for a while now, and that’s not a recipe worth messing with. That said, it will be strange to watch this team without veteran catcher Martin Maldonado calling the shots behind the dish — not to mention former manager Dusty Baker on the top step of the dugout — though I’d imagine Astros fans are looking forward to a higher percentage of Yainer Diaz at-bats going forward, and new skipper Joe Espada has been a huge part of this coaching staff for years.

While injuries have ravaged Houston’s rotation over the past year, the same pitchers generally remain on the roster in some form, even if that means on the injured list for a portion of 2024. And for the most part, the pitchers expected to step up and fill in have been in the organization for years, limiting the number of expected innings to be thrown by newcomers. That said, the addition of Josh Hader to an already loaded bullpen group will give the ninth inning a different look for ‘Stros fans, but Hader should be well-received in H-Town.

Seattle Mariners

No surprise here. The Mariners overhauled their offense through a hectic series of trades and the first multiyear deal ever given to a free-agent hitter by the Jerry Dipoto regime. With the departed Eugenio Suarez and Teoscar Hernandez having been true ironmen for Seattle in 2023, that’s more than 1,200 plate appearances out the door and in need of replacement. This was by design, of course, as Seattle sought players with more consistent contact ability than Suarez and Hernandez, who combined for 425 strikeouts.

Combined with the jettisoning of Jarred Kelenic to Atlanta, the Mariners lineup will look considerably different beyond the up-the-middle mainstays in Julio Rodriguez, J.P. Crawford and Cal Raleigh. Seattle will have fresh faces at third base (Luis Urias), second base (Jorge Polanco), DH (Mitch Garver) and two outfield spots (Luke Raley, Mitch Haniger). OK, Haniger is hardly a new name to the Mariners faithful, but for the purposes of this exercise, he counts as a new addition!

Unsurprisingly, there projects to be far more stability on the mound, where the rotation is primed to be one of the strongest in baseball. That said, it’s worth noting that the trade of Justin Topa (75 appearances in 2023) to Minnesota and the injury to Matt Brash (expected to start the year on the IL due to elbow inflammation) mean we could see manager Scott Servais call on some new names in the later innings in 2024. Gregory Santos, acquired from Chicago, is expected to be a big part of that once he returns from injury, as is free-agent signing Ryne Stanek, whom Seattle fans saw plenty of during his tenure with the rival Astros.

San Diego Padres

Sure, the faces of the franchise such as Manny Machado, Fernando Tatis Jr. and Joe Musgrove are still around. But the rest of this roster? Let’s just say it’s a good thing the Padres started the season a week early to give us all a head start on familiarizing ourselves with a drastically different team in 2024. In addition to the blockbuster trade of outfielder Juan Soto — who led the team with 708 plate appearances last year — to the Yankees, the Padres watched six of their eight most used pitchers depart in free agency, resulting in the 31% of returning innings that is by far the fewest in baseball. And with Trent Grisham also off to the Bronx in the Soto trade, the Padres return the fourth-lowest percentage of plate appearances in 2024, ahead of only the Marlins, Mariners and Angels.

While having this many key contributors hitting free agency at the same time was a bit of happenstance, it coincided with an organizational goal of toning down what had become a bloated payroll. In turn, A.J. Preller’s front office was busy filling the holes on the pitching staff in creative ways, beginning with the pitching-heavy haul from New York for Soto and ending with the trade for Dylan Cease. Overall, this seems like an awful lot of turnover for a team expecting to contend in 2024, but after all that went wrong in 2023 despite the boatload of star talent, maybe making big changes wasn’t the worst idea. Let’s hope new manager Mike Shildt had some quality icebreakers prepared so everyone could get to know one another in spring training.

Milwaukee Brewers

It’s one thing to refresh your roster after a dismally disappointing campaign, like the Padres, Yankees, Cardinals or Giants, or if you’re in the midst of a full-blown rebuild like the White Sox, searching for flippable trade assets or looking to give younger players more playing time. But what to make of the Brewers? Of the 11 teams with the lowest overall rates of return, Milwaukee was the only one that made the postseason in 2023.

The bold decision to trade staff ace Corbin Burnes to Baltimore for infielder Joey Ortiz and lefty DL Hall set the tone for what the Brew Crew will be prioritizing in 2024: letting the kids play. With Hall slotted into the rotation and Ortiz slated for the bulk of reps at third base, Milwaukee will attempt the delicate balance of remaining competitive while allowing a slew of rookies (Ortiz, top prospect Jackson Chourio) and sophomores (Sal Frelick, Brice Turang, Garrett Mitchell, Joey Wiemer) to find their footing in the big leagues. Rhys Hoskins and Gary Sanchez are two more fresh faces in the middle of the lineup, but the keys to Milwaukee’s short- and long-term future will be the development and performance of the young guns.