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 a top-6 payroll of $264 million, some of the most well-known players in the league and a recent history of consistent success, 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.  The postseason became an annual expectation for the Phillies under Thomson - but a bad month-long stretch has cost him his job.

Thomson had signed an extension through the 2027 season this past offseason, per The Athletic.

MORE: David Ross, Rocco Baldelli among best candidates for next Red Sox manager

Who is the Phillies' interim manager?

Mattingly, who became the Phillies' bench coach this offseason at age 65, is set to take over as interim manager, per Matt Gelb. 

While there has been some buzz about the connection between Dombrowski and Cora, the Phillies wrote in their statement that Mattingly will be interim manager "through the end of the 2026 season." 

According to the team, third base coach Dusty Wathan is being promoted to bench coach, and the franchise's Triple-A manager, Anthony Contreras, will take over as third base coach.

Mattingly is also the father of Philadelphia's general manager, Preston Mattingly.

Rob Thomson career record

• 355-270 (.568)

Thomson was a first-time manager when he took over for the Phillies in 2022. Since then, he's guided the Phillies to the postseason every year, including a 65-46 run in 2022 that led to a wild-card berth and run to the World Series.

However, Philadelphia has regressed in the postseason since then, losing in the NLCS in 2023, then the NLDS in 2024 and 2025, despite over 90 wins in each regular season.

Here's a look at Thomson's record:

*Took over midseason

How old is Rob Thomson?

Thomson is 62 years old and will turn 63 on Aug. 16, 2026. 

He took on his first MLB managing job at age 58 in 2022. 

MORE: Why did the Red Sox fire Alex Cora?