A year ago, Athletics closer Mason Miller was considered untouchable. On Thursday, hours before the trade deadline, the team with baseball’s best bullpen swung a big deal to land him.

Ever aggressive, the San Diego Padres have agreed to acquire Miller and left-handed starter JP Sears from the A’s in exchange for top prospect Leo De Vries, and right-handed pitchers Braden Nett, Henry Báez and Eduarniel Nuñez.

De Vries is 18 in High A and more than holding his own, hitting comfortably above the league average despite being the youngest regular at that level. He’s a switch hitter who’s clearly better from the left side, The Athletic’s Keith Law wrote in his midseason MLB prospect rankings where De Vries came in at No. 13, even though he hit for more power right-handed last year, with a strong left-handed swing that’s going to produce at least a ton of extra-base hits to the gaps. He’s a definite shortstop who might end up plus there, with a 60 arm and plenty of lateral range. He would have been a high school senior this spring had he grown up anywhere covered by the draft, and he’s already producing in High A; that alone would mark him as a potential star.

Nett, 23, was ranked as the Padres’ No. 7 prospect by The Athletic’s Keith Law before the season. Law noted at the time that “He works 96-97 with a slider and cutter, occasionally throwing a split-change that doesn’t move much, dominating righties but almost unusable against lefties. Left-handed batters had a .413 OBP against him last year, with an 18.7 percent walk rate and almost as many walks as strikeouts. He’s like a No. 3 starter against right-handed batters, and a guy who wouldn’t get out of A-ball against left-handed ones. He’ll end up in relief, and his role really depends on whether he can find something to limit the damage from lefties.”

In 17 starts for Double-A San Antonio this season, Nett has a 3.39 ERA with 86 strikeouts in 74.1 innings pitched.

Nett is the second-best prospect in the deal by a significant portion. He can really miss bats but has struggled against left-handers. Both Nett and Baez both have good fastballs but both have struggled with command in Double A. Nunez will likely join the A’s bullpen this season (maybe even right away), but he’s more of a middle relief guy.

The deal would dramatically reinforce a relief corps that leads the majors in ERA, WHIP and opponents’ batting average. The Padres this month sent a record three relievers — closer Robert Suarez and setup men Jason Adam and Adrian Morejon — to the All-Star Game, but president of baseball operations A.J. Preller has spent recent weeks canvassing the bullpen market in preparation for potentially bolstering the team’s greatest strength.

Miller has a 3.16 ERA and 48 saves over his first three big-league seasons. The 2024 American League All-Star leads the majors in average fastball velocity and ranks second in strikeout percentage. He also possesses some starting experience — Miller was a starter during his brief minor-league career and for six games as a rookie — and the Padres could attempt to try him in that role as soon as next season.

They’ll have time. Miller, 26, is under team control through 2029. The tall right-hander will reach salary arbitration this winter for the first time.

The A’s did not deploy Miller in a save situation on Wednesday night. Manager Mark Kotsay told reporters after the game that Miller’s unavailability was not injury-related.

If the deal is completed, the addition of Miller should enhance what already might be an unparalleled ability to shorten games. The Padres have been considering trading Suarez, who can soon opt out of his five-year, $46 million contract, to rebalance their payroll and address other needs. With the addition of Sears, a back-of-the-rotation starter, San Diego also is expected to trade starter and pending free agent Dylan Cease.

(Top photo of Mason Miller: Lachlan Cunningham / MLB Photos via Getty Images)