What do you get when you take a player with very good tools and off-the-charts makeup? Often, you get a player like Jarred Kelenic, who is slated to make his long-awaited Major League debut on Thursday.

The No. 1 prospect on the Mariners’ Top 30 prospects list and No. 4 on the Top 100, it would be easy to think Kelenic has been around forever given the amount of time and energy that has been used to discuss if and when he’d get called up to take his place in Seattle’s outfield for the first time. But Kelenic is just 21 years old and would be a college junior entering the Draft this year had he headed to college.

A product of the Wisconsin high school ranks, Kelenic was No. 10 on MLB Pipeline’s Draft Top 200 as the 2018 Draft approached. A Louisville recruit, Kelenic stood out for his advanced feel to hit, but it was unclear how much power he would generate from his 6-foot-1 frame or if he would be able to stay in center field long-term.