Jack Ralston hasn't gotten his opportunity yet, but it's coming

[Nathaniel Klaff]

Drafted in the seventh round in 2019 out of UCLA, Jack Ralston has spent his entire professional career as a reliever. After signing with the Miami Marlins as a minor league free agent this offseason, he is quickly becoming the latest example of the organization finding value in overlooked arms. Through 13 appearances this season with Triple-A Jacksonville, he owns a 1.27 ERA with a 0.98 WHIP and 31 strikeouts in just 21 ⅓ innings. The walks are still a little high at 4.64 BB/9, but compared to last season’s 6.75 BB/9, that's a significant improvement.

The Marlins bullpen has been pretty effective overall in 2026, but Ralston can help them reach even greater heights.

 

One adjustment has changed everything

With the AAA data we have from last season, it is easy to see what has changed for Ralston this year. In 2025, he threw all three of his pitches over 29% of the time (fastball 37.8%, splitter 32.3%, slider 29.8%). In 2026, everything has changed tremendously. His splitter usage has jumped all the way to 52.1% while his fastball usage has dropped to just 21.5%. His slider usage has stayed relatively similar at 26.3%.

Everything has followed with this adjustment. Ralston has done a tremendous job limiting damage this season, allowing just 0.42 home runs per nine while opponents are averaging only 4.22 hits per nine compared to 8.16 last year. The swing-and-miss has taken a huge step forward as well as he is now striking hitters out at a 13.08 K/9 clip, up from last season's 11.30. Additionally, the quality of contact against him has dropped as opponents are slugging just .173 after posting a .376 SLG last season.

While Ralston's walk rate is still a little high, hitters still have not been able to consistently reach base against him as opponents own just a .244 OBP against Ralston this season compared to a .371 OBP last year.

Overall, hitters own just a .417 OPS against him this year. Compared to a .747 OPS last season, it's clear just how effective the adjustments to his pitch mix have been.

 

When could we see him?

It is always tougher to determine sustainability with relievers as their results can fluctuate heavily from year to year, but through a 13-game sample, it is clear the adjustments Ralston and the Marlins made over the offseason have paid off.

The 28-year-old doesn't need to be waiting by his phone quite yet. The Marlins 40-man roster is currently full and Ralston isn't on it. 

However, this team has shown a willingness to demote struggling players and cycle through fresh arms when needed. During this current stretch of 26 games in 27 days, pitching depth will inevitably be leaned on. Ralston could be next in line to debut.

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