Kelly experienced the sensation while throwing on Saturday and alerted the Diamondbacks’ athletic training staff. Early indications are a strain in the teres major.

“It’s a really light sensation, but in my mind I feel like I can just tell it was different than something usual,” Kelly said, according to ESPN. “Obviously during the course of the season, during the course of our lives, we’ve all felt things in our arm when we’ve let go of a baseball. I think at this point in my career I’m pretty decent at being able to tell the difference on what’s OK to keep going through and then what’s not.”

Kelly picked up right where he left off last season with a fantastic start to his 2024 campaign. The right-hander is 2-0 with a 2.19 ERA in four outings, three of them quality starts. He has 21 strikeouts to six walks and has not allowed more than two runs in a single start.

Kelly has been among the MLB’s best and most consistent starting pitchers since 2022. The 35-year-old has a 3.26 ERA in 67 starts in that span, making 30 starts in 2023 after a league-leading 33 in 2022.

During Arizona’s run to the World Series last season, Kelly posted a 3-1 record with a 2.25 ERA. He saved his best for last, tossing seven brilliant innings in a Game 2 win over the Texas Rangers in the World Series, the D-backs’ only victory of the series.

Pitching injuries piling up for Diamondbacks

Losing Merrill Kelly for an extended time would be a huge blow to the Diamondbacks. The defending NL champs are already dealing with multiple injuries on the pitching side and recently placed starter Ryne Nelson on the injured list after he took a comebacker to the elbow on Thursday.

Eduardo Rodriguez has yet to make his D-backs debut as he continues to recover from a left shoulder strain he suffered during spring training. Arizona shifted him to the 60-day injured list last week and there is no clear timetable for his return.

On top of that, closer Paul Sewald remains out with an oblique strain. Overall, the Diamondbacks have five pitchers on their 40-man roster who are currently on the injured list.

If Kelly is out for a while, the pressure mounts on the rest of Arizona’s pitching staff. Diamondbacks pitching is middle of the pack with a 3.96 ERA, ranked 14th in the MLB.

The debut of Jordan Montgomery last Friday was a welcome sight for the D-backs. He registered a quality start in a win over the San Francisco Giants, allowing one run across six innings. Montgomery will be asked to give more of the same with pitching injuries becoming a problem.

The Diamondbacks have weathered the storm with an 11-12 record. Making it back to the playoffs will be no easy task in a top-heavy National League and will be even harder if Arizona can’t keep its arms healthy.