Dylan Cease Trade: Why Did Padres' New Starter Struggle in 2023?

Were early mechanical issues and a diminished breaking ball responsible?

The San Diego Padres just acquired a pitcher who went 7-9 with a middling 4.58 ERA in 2023. So why is the Dylan Cease trade being heralded as an unqualified blockbuster?

The answer requires taking a long view — not just of Cease's career, but of how he compares to other starting pitchers around the league by modern standards.

The key stat for Cease last year: his 177 innings pitched were 31st overall and made him one of just 44 pitchers to qualify for the ERA title. Among Padres starters, only Blake Snell was as durable last year. 

Not only is Snell gone, so are Seth Lugo (146.1 IP in 2023), Michael Wacha (134.1) and Nick Martinez (110.1). For all the raw talent on the Padres' pitching staff, replacing four of the team's top five innings-eaters in 2023 was a daunting task.

For all his struggles last year, Cease is well-suited to fill the Padres' greatest need: innings. Writes FanGraphs' Ben Clemens:

Whether he’s an ace depends heavily on your definition of ace, but he’s inarguably a good starting pitcher. Over the past three years, he’s averaged 32 starts, 175 innings, and 4 WAR. That’s a top-10 pitching line, and his peripherals mostly match the headline numbers, so it’s not like he’s been doing it with smoke and mirrors.

Cease posted an outstanding ERA (2.20) and FIP (3.10), among other key stats, for the White Sox in 2022. So why exactly did he struggle in 2023?

Start with his primary secondary pitch – his slider, writes South Side Sox:

Cease’s fastball didn’t lose much spin or induced vertical break, which is good. But still, raising your fastball usage while your velocity is down doesn’t seem to make sense — until you realize that his slider was also in flux. Looking at Cease’s Stuff+, it confirms what result-based stats told us. Each of his four pitch types were worse in 2023, with his fastball representing the lowest drop-off (127 to 125) and his slider representing the largest (a massive drop, from 136 to 120).

The Athletic chronicled some mechanical issues Cease had early last season that might have fed into the poor underlying numbers:

“Dylan was rotating too soon. He was opening up. He was losing a little bit of his hip/shoulder separation, and … he was pulling his head. So his numbers on his fastball are slightly down, but his efficiency on his fastball is a little bit further down than it has been.”

— Chicago White Sox pitching coach Ethan Katz,

via The Athletic

By the end of last season, Cease was speaking about those mechanical issues in the past tense. Perhaps not coincidentally, the White Sox brought in a new pitching advisor, Brian Bannister.

Either way, the Padres must have liked what they saw in the 27-year-old more than his 2023 numbers would suggest.