Career-worst outing sinks Casey Mize in Padres debut against Diamondbacks

ARIZONA — The highly anticipated debut of Casey Mize in a Padres uniform sparked excitement and gave San Diego fans their first look at what made the right-hander the No. 1 overall pick in the 2018 MLB Draft. His first test came against the division-rival Arizona Diamondbacks, with an opportunity to help the Padres move into a tie for second place in the National League West.

Unfortunately for the 2025 All-Star, his first outing in the Brown and Gold ended in disappointment as the San Diego Padres fell to the Arizona Diamondbacks 10-4 Wednesday night at Chase Field.

Mize took the mound for the first time since being acquired from the Detroit Tigers just minutes before the conclusion of Monday's trade deadline. The 29-year-old out of Auburn ran into a relentless Arizona lineup and endured the worst start of his career, surrendering eight earned runs on nine hits while walking three and striking out one in 3 1/3 innings.

Entering Wednesday, Mize had allowed just seven earned runs over his previous 28 1/3 innings, a stretch spanning five starts across four weeks. In his final outing with Detroit, the right-hander tossed six innings and allowed one run on three hits.

Although Mize escaped trouble in the first two innings by stranding four Arizona runners, the Diamondbacks broke through in the third on Gabriel Moreno's sacrifice fly and Tim Tawa's solo home run, the first baseman's second homer of the series and sixth of the season.

The fourth inning, however, quickly unraveled for Mize. Arizona collected five consecutive hits and erupted for six runs to extend its lead to 8-0. After issuing his third and final walk to Moreno to bring in a run, Padres' manager Craig Stammen ended Mize's night and bring in reliever Kyle Hart.

“Not the first impression I wanted to make for my teammates and for the fans,” Mize said to MLB.com's AJ Cassavell. “Pretty tough time to have the worst start of my career. I just put us in a really tough spot, didn't give us a chance to win. So, frustrated and embarrassed by that.”

The eight earned runs were the most Mize has allowed in a game during his six-year career, surpassing the six runs he surrendered on three previous occasions — twice against Kansas City in 2021 and 2024 and once against Minnesota during his rookie season in 2020. The nine hits also were the most he had allowed in a start since July 2025, when he gave up 10 over four innings against the Pittsburgh Pirates.

The lone encouraging sign came from Mize's fastball velocity, which averaged 93.4 mph — 1.5 mph higher than in his previous start, when it sat at 91.9 mph and dipped below 90 in the later innings.

“It’s pretty frustrating for me,” Mize said. “But I’ll put in a good week’s work and I’ll be better next time.”

While the spotlight centered on Mize's career-worst outing, Arizona rookie Mitch Bratt quietly turned in the best performance of his young major league career. The 23-year-old left-hander made the sixth start of his rookie season and dominated a red-hot San Diego lineup, tossing seven innings, allowing one hit and striking out nine to earn his first major league victory. The rookie delivered in a game that could carry significant postseason implications.

According to OptaStats on X, Bratt became the only rookie left-hander to throw at least seven innings, allow no more than one hit, strike out at least nine batters, throw fewer than 100 pitches and earn the win. 

Despite entering the ninth trailing 10-0, third baseman Gage Workman, the other piece acquired from Detroit in the Mize trade, laced a slider from reliever Kevin Ginkel into the left-center field gap for a bases-clearing double on the first swing of his Padres career.

A few batters before Workman's extra-base hit, Fernando Tatis Jr. crushed his ninth home run of the season, a 465-foot blast that put San Diego on the board.

The Padres fell to 59-56 and dropped two games behind Arizona and Philadelphia for the third and final National League Wild Card spot.

San Diego will look to salvage a split of the four-game series Thursday night at Chase Field. Veteran right-hander Walker Buehler will take the mound for the Padres in search of his seventh win, while Arizona counters with left-hander Kohl Drake, who will be seeking his first victory of the season.