Major-league sources said Wednesday, Oct. 14, that Long, 59, and Dickerson, 61, had been told they would not return. The team was expected to announce the coaching changes at a news conference Thursday at Citizens Bank Park.

Both joined Philadelphia before the 2022 season, when Joe Girardi was manager, and stayed through Rob Thomson’s tenure and Mattingly’s interim stretch. Long also signed a three-year contract extension last offseason and was close with several key Phillies hitters, including Kyle Schwarber, Trea Turner and Bryce Harper.

The staffing changes come after the offense and defense weakened sharply. Philadelphia scored three runs or fewer in 72 games, including the postseason, and ranked 19th in Major League Baseball in runs, 22nd in OPS and 23rd in on-base percentage. The team ranked 28th in on-base percentage against right-handed pitching. Turner had the worst season of his career.

Over the previous four seasons, with much of the same personnel, the Phillies had ranked no lower than eighth in runs per game or OPS. The team’s results this season point to a possible shift in its approach, with Mattingly expected to have a voice in choosing the next hitting coach. A .307 career hitter, he takes over after leading the club to a 79-55 record as interim manager.

Dickerson had been credited with helping Alec Bohm become a steadier defensive third baseman and guiding Harper’s move to first base in 2023 as Harper recovered from Tommy John surgery. But Philadelphia’s infield struggled overall: its players finished 44 runs below average in defensive runs saved, the worst mark in the majors. Turner also regressed at shortstop after the best defensive season of his career.

Major-league sources said the Phillies are believed to be seeking a more data-driven approach to infield defense. Both Long and Dickerson are well regarded around baseball and could find coaching work elsewhere.