A promising pitching prospect is about to join the Mariners straight from Double-A Arkansas.

No, sorry, it’s not one of those promising young arms.

Kade Anderson and Ryan Sloan, the Mariners’ Nos. 1 and 2 pitching prospects, are both showing dominant potential pitching for the Arkansas Travelers, and both could be in line for a big-league promotion at some point this summer.

But not today.

The Mariners, instead, announced Saturday that they are promoting right-handed reliever Nick Davila from Double-A to the big-league bullpen.

Davila, 27, will make his MLB debut when he appears in a game for the Mariners.…