Is Sunday Zac Gallen's Final Turn in Rotation as a Diamondback?

It would be hard to find a bigger mismatch on paper right now than Gallen versus Skenes.

The Pirates' ace has the lowest ERA (1.91) among all qualified starters in MLB. Gallen (5.58) has the second-worst.

Skenes has the lowest home run per nine rate of any pitcher in MLB, 0.43, while Gallen has the fourth-highest at 1.71

Skenes' Fielding Independent Pitching (FIP) is 2.40, the second-best in MLB. Gallen's is 4.86, the sixth-worst.

Skenes has been worth 4.2 Fangraphs WAR and 5.4 Baseball Reference WAR. Gallen has 0.0 WAR in both website's calculations, in other words the very definition of replacement-level.

And yet there is hope. In a statistic that illustrated the unpredictable nature of baseball, the Pirates are just 10-11 in games started by Skenes. That is due to receiving just 3.1 runs per game of support from his offense.

He has four "tough losses" in which he pitched a quality start, and took the loss anyway. There are four other games Skenes left in line for the win, only to have his bullpen blow the game.

Between May 1 and July 11, Skenes made 14 starts and posted an impossible 1.84 ERA, but somehow went 1-6 with seven no-decisions. He broke that run with six shutout innings against the Tigers on July 21 to pickup his fifth victory.

One other point to note is the Pirates have not allowed Skenes to go over 88 pitches in any of his previous five starts. If the D-backs can somehow work counts and force him into a shorter outing, the Pirates' bullpen may be somewhat taxed.

As for Gallen, he had two very good starts July 1 and July 7 against the Giants and Padres, throwing 13 innings, striking out 19, and giving up just one earned run.

He followed that up with two clunkers however, giving up six earned runs to both the Angels and the Astros in 11 total innings. Inconsistency has been the hallmark of Gallen's 2025 season.

It's been a tough pill to swallow for Gallen, the Diamondbacks, and their fans. From 2022 to 2024 the right-hander went 42-19 with 3.22 ERA, finishing in the top five of the Cy Young voting in both 2022 and 2023. He was a key member of the 2023 NL Championship squad.

But trouble began to emerge last year, and this season he's been in free fall. Just months away from becoming a free agent for the first time, he is considered a rental trade target. But both the expected return and his future free agent contract are likely to be greatly diminished.

Diamondbacks vs Pirates Lineup

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Diamondbacks and Pirates Bullpens

The D-backs' bullpen is in pretty good shape, workload-wise. They used two relievers on Saturday, Andrew Saalfrank and Kendall Graveman. They needed to cover just four outs thanks to Merrill Kelly going 6.2 innings.

Anthony DeSclafani threw four innings on Friday and will not be available, But Kevin Ginkel should be, as he threw one inning on Friday and was off Saturday.

The Pirates' best two relievers, David Bednar and Dennis Santana, each worked two nights in a row, Friday and Saturday.

The Pirates used three other relievers on Saturday and two more beside Bednar and Santana on Friday. That extra workload could come into play if it's another close game late on Sunday.

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