Ryne Nelson Must End D-backs' Losing Streak vs Pirates

The Arizona Diamondbacks fell below .500 in St. Louis this weekend, and were the victims of their first sweep in more than a full calendar year. On a five-game losing streak, they'll look to right the ship at home against the Pittsburgh Pirates on Monday with an early 5:10 p.m. first pitch.

The D-backs are now 26-27, and have failed to collect the big knocks when needed, while bullpen issues have persisted. While the schedule does ease up with a three-game set against the 19-35 Pirates, Arizona needs to put together a hot streak — quickly.

Pitching Matchup

RHP Ryne Nelson (4.60 ERA)

Right-hander Ryne Nelson has been yanked around this season, but he's been an admirable arm for the most part when the D-backs have called upon him. Due to the starting rotation's depth to begin the year, Nelson was relegated to long relief, but an injury to left-hander Eduardo Rodríguez necessitated Nelson's return to the rotation.

Nelson was the D-backs' best starter in the second half of 2024, pitching to a 3.23 ERA post-All-Star Break. He's been used in long relief, short relief and as a starter in 2025, and although his 4.60 ERA is below average, his 3.56 FIP suggests he's been better than the raw results.

That was on full display his last time out. Nelson tossed five innings of one-run ball on just 71 pitches against the vaunted Los Angeles Dodgers. He was able to limit them to just three base hits, and though he only struck out two, he pitched to contact in a calmly efficient manner.

Nelson is likely still ramping up to higher pitch counts due to his relief usage, and could be limited to 65-70 pitches again Monday. The specific length of his outing is likely to be determined by efficiency and pitch count.

LHP Andrew Heaney (2.91 ERA)

Outside of Paul Skenes, left-hander Andrew Heaney has been one of the Pirates' most effective arms. He's recorded four Quality Starts, and has gone at least six innings five times, even pitching into the eighth once.

Arizona has struggled against left-handed pitching this season, and Heaney has been an effective southpaw, to say the least. However, Heaney's 2.91 ERA is undermined by his peripherals. His FIP is 4.04, his expected FIP is 4.34, and his expected ERA is 4.37. His batting average on balls in play (BABIP) is an unsustainable .234.

By just about every metric other than raw ERA, Heaney has hovered around league average. He can garner chases at times, but isn't a strikeout arm with just 6.79 strikeouts per nine. His hard-hit rate and surrounding metrics are all essentially average, as is his ground ball rate.

Heaney's fastball has dipped to 90 MPH, but he still relies on it 44% of the time. If he's not hitting his spots, that fastball could become batting practice for the D-backs if they're able to avoid weak contact.

Lineup