It didn't take Midland long to put runs on the board, as first baseman Viosergy Rosa opened the scoring with a solo home run in the bottom of the second. The RockHounds would then tack on two more runs before the end of the frame, both coming with two outs, with center fielder Brett Vertigan and second baseman Max Schrock both delivering RBI knocks.
In the fifth, outfielder Tyler Marincov connected on a solo home run, his first of the postseason, to extend Midland's lead to 4-0.
The Naturals threatened in the top of the sixth, putting runners on first and second with two outs, only to see RockHounds starter James Naile pick off lead runner Corey Toups to end the frame.
Naile, meanwhile, couldn't have thrown the ball any better in his first postseason start. The 23-year-old right-hander scattered two hits over six scoreless innings, walking two and strikeout out four, while throwing 52 of his 85 pitches for strikes. The 2015 20th-rounder also generated 12 ground-ball outs against zero fly outs in the outing.
Replacing Naile on the mound in the seventh was Kyle Finnegan, who proceeded to allow a hit to Naturals first baseman Ryan O'Hearn (Royals No. 8) and then loaded the bases with a pair of walks. Trey Cochran-Gill relieved Finnegan and immediately induced a ground-ball double play followed by a flyout, though Northwest Arkansas did push across a run in the frame.
Cochran-Gill returned to the mound to throw a scoreless eighth inning, while closer Jake Sanchez struck out the final two hitters of the game to record the save.
The RockHounds had four players collect two hits, including Marincov, who went 2-for-4 to raise his postseason average to a team-best .438. The 24-year-old collected 14 hits in that span while hitting safely in seven of Midland's eight playoff contests.
A's No. 6 prospect Richie Martin also had a strong game, going 2-for-3 with a double and also reaching base once via a walk, while Yairo Munoz (A's No. 7) finished 2-for-4. The infield duo batted .333 and .387 for Midland in the postseason, respectively.
Northwest Arkansas collected only three hits in the loss, with O'Hearn and Toups (Royals' No. 30) notching one apiece. O'Hearn, who batted .375 with three homers, three doubles and eight RBIs in the postseason, also scored the Naturals' lone run.