Rangers call-up Kumar Rocker s...

Kumar Rocker's path from being college baseball's most electric freshman to his MLB debut ended up being more eventful than anyone wanted, but the end result looked mighty impressive on Thursday.

The No. 3 pick of the 2022 MLB Draft (and No. 10 pick of the 2021 Draft) struck out seven for the Texas Rangers while allowing three hits, two walks and an earned run in four innings of work in a 5-4 win over the Seattle Mariners on Thursday. On display were upper-90s heat and some wipeout breaking pitches.

He also made history as MLB's first player of Indian descent.

Rocker's most impressive pitch was easily his slider, which MLB Pipeline rates as a 70 on the 20-80 scouting scale. Per Baseball Savant, Rocker threw 33 sliders out of his 74 pitches and generated 13 whiffs on 21 swings.

That's tied for the eighth-most swing-and-misses on a slider in a game this season, which, again, Rocker did in only four innings. No player had generated 10 slider whiffs in fewer than 78 pitches all season.

That's a loud debut for a player who has plenty of backstory.

Kumar Rocker's road to MLB was bumpy

Rocker looked like a potential No. 1 overall pick in 2019, when he earned Most Outstanding Player in Vanderbilt's College World Series title. That was after a 19-strikeout no-hitter against Duke in the Super Regional round.

Rocker's stuff was tantalizing, but concerns about a velocity dip in his junior year, long-term durability concerns and questions about the depth of his arsenal resulted him in falling to the Mets at 10th overall in the 2021 MLB Draft. Then the Mets pulled back an above-slot $6 million offer upon reviewing his medicals, which were not available pre-draft.

Rather than return to Vanderbilt, Rocker trained by himself, then signed with the independent Tri-City ValleyCats ahead of the 2022 MLB Draft. He was surprisingly selected third overall by the Rangers and landed a $5.2 million signing bonus.

The Mets were seemingly vindicated when Rocker was announced to need Tommy John surgery in May 2023. New York used their compensation pick for failing to sign Rocker on Georgia Tech's Kevin Parada, a bat-first catcher who is currently hitting .209 in Double-A.

Rocker returned quickly by Tommy John standards, making it back to the mound in July and rocketing up the Rangers' org chart until the team announced he was big-league bound. Many people have been waiting years to see Rocker pitch in MLB, and his first game was a good sign the wait (and turbulence) will be worth it.