The Rockies will promote top pitching prospect Jon Gray to the majors on Tuesday, MLB.com’s Thomas Harding reports (Twitter link). Gray, a 23-year-old right-hander, will make his Major League debut that evening at Coors Field in a start against the Mariners.

Rockies GM Jeff Bridich expressed some caution over Gray’s timeline to the Show earlier this month, saying that he wanted Gray to be fully prepared before coming to Denver, possibly influenced by how Eddie Butler, another Rockies prospect, has struggled since coming to the majors. Given how the Rockies have long been lacking in reliable starting pitching, it’s hard to fault Bridich for being careful with such a vaunted homegrown prospect, though it remains to be seen how Gray will adjust to the unique challenge of Coors Field.

Gray’s impressive performance in July may have swayed Bridich’s mind, as the righty has posted a 2.70 ERA and 43 strikeouts (against just 13 walks) over his last 30 innings for Triple-A Albuquerque. For the season as a whole, Gray has a 4.33 ERA, 8.7 K/9 and 2.68 K/BB rate over 114 1/3 innings; respectable numbers considering it’s his first taste of Triple-A action and the Pacific Coast League is notoriously hitter-friendly.

Colorado selected Gray with the third overall pick of the 2013 amateur draft, and he’ll join Kris Bryant, Marco Gonzales, Chi Chi Gonzalez, Michael Lorenzen, Corey Knebel and Matt Marksberry as 2013 draftees to reach the Major Leagues. A University of Oklahoma product, Gray is a 6’4″, 235-pound righty who the 2015 Baseball America Prospect Handbook projected as a possible No. 2 starter at the big league level. According to the BA Handbook, Gray owns an above-average changeup, a slider that could also become an above-average out pitch and a booming fastball that touched the 102mph plateau as recently as 2013, though he was working in the 94mph range last season.

Gray entered 2015 ranked highly top-100 prospects lists from MLB.com (#16th), ESPN’s Keith Law (#22), Baseball America (#24) and Fangraphs (#28). The midseason BA top-50 prospects list bumped Gray down to 35th, noting that “scouts who have seen Gray wish they saw dominant outings on a more consistent basis.” It’s worth mentioning that this list was released on July 7, prior to much of Gray’s recent strong work.