The roster quirk the Brewers and Mariners share heading into the 2025 MLB playoffs

The Milwaukee Brewers and Seattle Mariners, two teams vying for their first World Series title, will both head straight to the Division Series after earning first-round byes in the 2025 MLB playoffs. The Mariners, who earned the second overall seed in the American League, are headed to the postseason for the first time since the 2022 season, when they were swept by their division rivals, the Houston Astros, in the ALDS.

The Mariners and Brewers will forever be connected by their shared history. The Brewers began their franchise history as the Seattle Pilots, but relocated to Milwaukee after one season. Just seven years later, the Mariners were formed as an expansion team, thus returning professional baseball to the city of Seattle.

However, the Brewers and Mariners’ commonalities don't stop there; the two teams' rosters are built very similarly heading into October.

Brewers and Mariners lead MLB postseason field in rostered players acquired via trade

MLB.com published their annual "How They Were Built" article this morning, detailing how each of the postseason teams’ anticipated playoff rosters are constructed. It's an excellent read that you should be sure to check out (link provided below), but it revealed another similarity that the Brewers and Mariners share.

Here's how the 2025 postseason teams were built

As noted in the article, the Brewers and Mariners lead all postseason teams in players acquired via trade. Both Seattle and Milwaukee have 14 players on their rosters that were added to the organization through a trade.

The roster quirk should come as no surprise for Mariners fans who are well aware of Jerry Dipoto's, their president of baseball operations', affinity for swinging deals. Meanwhile, the Brewers often rely on acquiring players who have struggled to find success elsewhere, buying low on their services, and turning them into everyday players (see Quinn Priester and Andrew Vaughn).

So perhaps it's no surprise that the Brewers and Mariners roster the most players acquired via trade of any team in the 2025 playoffs, but it does reveal how smaller payroll teams must navigate the world of roster construction to field a competitive team.

The six teams with the highest payrolls in the 2025 MLB postseason average 9.5 players on their roster who were signed as free agents. Meanwhile, the six teams with the lowest payrolls in the playoffs average just over 5 players on their roster who joined their squad through free agency. It's certainly not always the case that free agents are more expensive than trade acquisitions, but more often than not, signing a player who has the opportunity to sign anywhere will result in teams overvaluing their contract. In other words, higher payroll teams have the ability to lure free agents away from other teams with a contract that is worth more than that player’s expected value.

With players like Christian Yelich, William Contreras, Freddy Peralta (who ironically was acquired from the Mariners), Caleb Durbin, Priester, and Vaughn leading the charge this October, the Brewers' front office has constructed an impressive postseason roster by mainly using the art of the swap. Doing so takes a run of successful deals, which is exactly what the Brewers have done in recent years; arguing that the Brewers lost any of the trades that resulted in the players listed above would be a difficult task.

Constructing a playoff roster is no easy feat, but doing so with the limited resources that Matt Arnold and company have at their disposal is even more complicated. They are forced to rely on executing savvy trades that constantly result in the Brewers adding a cheap, controllable, everyday player to their roster. The combination has led to the Brewers entering the 2025 playoffs with the best record in baseball.