What's behind Steven Matz's rebirth?

The left-hander has pitched like an ace since rejoining the rotation, and there are encouraging reasons for that

Lefty Steven Matz has thrived since returning to the rotation from a bullpen exile that lasted roughly a month and change. That’s welcome news given that Matz will probably figure prominently in the rotation mix for 2024. As such it’s worth pondering whether the changes Matz has made might make this newfound success sustainable across a larger sample. 

Matz’s first 2023 stint as a starter spanned 10 starts from April 4 through May 24, and over that stretch he registered an ERA of 5.72 and an FIP of 4.80. Since being reinstalled as a starter in the second week of June, he’s made six starts as of this writing, and in those starts he boasts an ERA of 1.65 and an FIP of 2.69. Given his strides at the FIP level (FIP, or fielding-independent pitching, attempts to peg a pitcher’s “deserved” ERA by stripping away the effects of defense and batted-ball randomness), you can probably guess that he’s also improved at the underlying skills. Consider how his first rotation stint compares to his current one in terms of some key metrics: