Why did the Phillies fire Rob Thomson? Philadelphia parts ways with manager after 9-19 start

Nearly four years ago, the Philadelphia Phillies caught fire and won the NL pennant when they made a midseason manager change, naming Rob Thomson the interim. They'll be hoping for similar success in 2026.

Philadelphia fired Thomson on Tuesday after a 9-19 start to the season, per Matt Gelb, a move that comes after a recent 10-game losing streak. Thomson is already the second MLB manager fired this season, with the Red Sox parting ways with Alex Cora over the weekend,

Don Mattingly, with plenty of managerial experience, is set to take over for Thomson as the Phillies look to recover from a dreadful start in 2026.

Here's what to know about the Phillies firing Thomson after around 3.5 seasons.

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Why did the Phillies fire Rob Thomson?

In Thomson's tenure, Philadelphia has been one of MLB's best overall teams and a consistent NL East threat — since Joe Girardi was fired by the team in June 2022, with Thomson stepping in, the Phillies have made four-straight playoff appearances with two division titles and a World Series berth.

However, all of that success has come to a screeching halt to open the 2026, with the team fighting through a rough April. After bringing back virtually the same core of star players this offseason — led by Bryce Harper, Kyle Schwarber, Trea Turner, Zack Wheeler and Aaron Nola — the Phillies have struggled to a 9-19 start, owning an MLB-worst -54 run differential. 

For a team with some of the most well-known players in the league and a recent history of consistent successs, it's been an ugly start. Only one player on the roster is hitting over .300 (backup catcher Garrett Stubbs), while starters Jesus Luzardo, Aaron Nola and Andrew Painter have ERAs over 5.00.

One way or another, those struggles were bound to lead to changes for a team with high expectations, and Thomson became the scapegoat, for the time being. While Dombrowski didn't make any significant lineup changes in the offseason despite a flat offense in last year's postseason, Thomson is the first big change Philadelphia is making in response to its poor start.

Mattingly, who became the Phillies' bench coach this offseason at age 65, is set to take over as interim manager, per Matt Gelb. The postseason became an annual expectation for the Phillies under Thomson — but a bad month-long stretch has cost him his job.