[1][2] He was the grandson of Walter O'Malley, who had owned the Brooklyn Dodgers of Major League Baseball (MLB) and relocated them to the West Coast to become the Los Angeles Dodgers,[3] and nephew of Peter O'Malley who inherited the team, along with Seidler's mother.

[10] The team increased spending in an attempt to contend for a championship, acquiring Matt Kemp, Justin Upton, and James Shields.

[3] Seidler increased the Padres' payroll to $214 million for the 2022 season, which was the sixth-highest in MLB.

He authorized the acquisitions and contract extensions to star players, including Xander Bogaerts, Yu Darvish, Manny Machado, Fernando Tatís Jr., Juan Soto, Josh Hader, and Joe Musgrove.

[14] In September 2023, Seidler announced that he had undergone a medical procedure which would prevent him from attending any further games in the 2023 season.