It's time for the Mariners to give Jhonathan Diaz a shot

Bryan Woo is still rehabbing, and the Emerson Hancock experiment has not gone very well. Could Jhonathan Diaz be next man up?
Jhonathan Diaz, Mariners Photo Day
Jhonathan Diaz, Mariners Photo Day / Steph Chambers/GettyImages

The Mariners' starting rotation was ranked number one in the American League by the Athletic this past offseason after posting a 3.89 ERA as a unit last season. 2024 has been underwhelming with a 4.68 ERA early, anchored by Emerson Hancock's 7.98 ERA in three starts. As a Georgia Bulldog, Hancock was throwing in the high nineties but now throws in the low to mid-nineties.

The slider is average and the changeup is playable, but he doesn't have a strikeout pitch and he ranks in the 13th percentile in chase rate this season. It's apparent to me and many others that Hancock will likely never be a playoff-caliber starter and may not even stick around in the big league rotation all season.

It's time for the Mariners to give Jhonathan Diaz a chance

If the Mariners do want to send Emerson down to Tacoma, Jhonathan Diaz is the logical choice to replace him and he impressed in the spring. Diaz has a 0.38 ERA and 10.1 K/9 in four starts for Tacoma in 2024 and owns a career 4.05 ERA at the AAA level in 55 games. In his brief stints at the MLB level, the main concern for Diaz has been command. His strikeout rate is 1:1 with his walk rate (6.1/9) in 11 big league games. However, Diaz only has one walk in four starts this season and seems to have his best command in years, if not ever. It'd be a worthwhile experiment to see if his newfound command translates to success, and it'd be more meaningful than another Hancock start.

The Mariners' mediocrity so far this season has stemmed from both the offense and the starting rotation that was expected to be the best in the American League this season. A 4.68 ERA won't get the Mariners to an AL West Crown, but I am not concerned about George Kirby. I'm a little concerned about Luis Castillo, but I believe he's still a #2 or #3 starter right now.

I am concerned, however, with the lack of rotation depth after Bryan Woo. Seattle has Hancock, Diaz, Levi Stoudt, and Dallas Keuchel. I prefer Diaz out of that group right now, especially with the way he's been throwing. He's the only one I envision putting together quality innings, and he could be a #6 on the chart all year if everything clicks.