Grayson Rodriguez, the Orioles recently announced his resignation following the game.

SARASOTA, Fla. — On the heels of a promising rookie campaign, Orioles starter Grayson Rodriguez is developing a new two-seam fastball he plans to integrate into his existing five-pitch arsenal this season. The right-hander debuted the pitch in his first spring start Tuesday against the Detroit Tigers and left the mound pleased with how it played.

“I threw it a decent amount,” Rodriguez said after his outing. “Something new, still going to work on it. Felt a little bit different throwing a fastball with a different grip but it’s something new to try that I think we’re going to keep doing this year.”

Rodriguez, 23, overcame a slow start in 2023 to finish the year as the Orioles’ choice to start Game 2 of the American League Division Series. Though he didn’t carry over his success into the postseason, he finished the regular season with a 2.58 ERA and 1.10 WHIP over his final 13 starts to show his lofty prospect status was warranted.

Now hoping to put together his first full season in the majors, Rodriguez is trying to add another element to his pitch mix that will keep hitters from sitting on his primary four-seam fastball. He threw the four-seamer 49.6% of the time last season, the most of any pitch by a wide margin. Opponents also had the most success against it, batting .342 off it.

Still tinkering with the grip, Rodriguez is trying to nail down a pitch shape that mimics the four-seamer but has more horizontal movement. He wants to avoid it moving like a sinker, a pitch similar to a two-seamer that has some vertical drop to it.

“I really don’t want a sinker,” Rodriguez said in the clubhouse Wednesday. “I want more of a running fastball … A sinker would obviously have a low vertical movement or a low vertical height with run. I’m looking to keep the vertical height about the same adding horizontal movement so keeping a true two-seamer, not necessarily a sinker.”

When he brought it out Tuesday, the results were eye-popping. Manager Brandon Hyde noted that despite not commanding his breaking balls well, Rodriguez got ahead of hitters early with his fastballs. He sat around 99 mph and hit triple digits in two innings of work.

“Tough to tell because he’s throwing 99,” Hyde said of how the pitch played. “So, I couldn’t really tell from my angle but hitting 100 a few times. The fastball was really good. It was just, like I said, tough time staying ahead in the count. A few too many three ball counts.”

Rodriguez decided to add the pitch to his arsenal this offseason while working out with mentor and former MLB pitcher Josh Tomlin. He brought the idea to the Orioles and they agreed to work with him on it.

“Obviously, being a four-seam guy, hitters are going to go up there expecting something straight. So, throwing them off of that sightline.”