Hours before adding a first-round pick to the fold in the MLB draft, the Orioles are promoting last year’s top selection.

Baltimore is moving shortstop prospect Jackson Holliday, the No. 1 overall pick in last year’s draft, to Double-A Bowie, a team source told The Baltimore Banner. In addition, third baseman Coby Mayo and right-hander Chayce McDermott will be heading to Triple-A Norfolk.

This is the second promotion Holliday, MLB Pipeline’s top-ranked prospect, has received this season. After hitting .396 in just 14 games with Single-A Delmarva to start the year, the 19-year-old phenom crushed High-A pitching in 57 games with the Aberdeen IronBirds. Holliday hit .314 with five home runs, producing a .940 on-base-plus-slugging percentage.

Holliday, who has also played second base and third base in the minors, appeared in the All-Star Futures Game on Saturday, striking out in his only plate appearance.

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Mayo, who ranks 76th in MLB Pipeline’s top 100, hit .307 with 17 home runs in his second season with Bowie. The 2020 fourth-round pick joins a crowded Norfolk infield that includes prospects Joey Ortiz, César Prieto and Connor Norby.

McDermott, who was acquired last August in the trade that sent Trey Mancini to the Astros, posted a 3.56 ERA in 16 appearances for the Baysox this season. His strikeout numbers — 11.6 per nine innings — are gaudy, while his walk numbers — 5.8 per nine — have been troublesome.

paul.mancano@thebaltimorebanner.com