After retiring the first batter of the inning, though, Nakaushiro walked the bases loaded before Ryan Casteel unloaded them with a grand slam to give the Mariners a 6-5 lead.
The Mariners were not done as Jay Baum doubled home a pair of runs and Adam Law capped the scoring with a single to left-center to score Baum.
The only downside for Miller is he would've liked to have gone deeper in the game, as he lasted just 3 1/3 innings before his pitch count of 73 forced him to exit.
"It's nice to get some swings and misses," Miller said. "Strikeouts are always nice. It kind of lets you know where your stuff is at. Today I felt sharp, but I wasn't near as efficient as I need to be. I kind of got into some deep counts. My pitch count was high after three innings. I guess more importantly, I got my work in and got my pitches in, but overall I felt good but still need to do a better job of getting guys out a little quicker."
The Mariners scored a run off Miller in the first when Jarrod Dyson led off the game by drawing a walk and came around to score one batter later when Kyle Seager drove a double into the gap in right-center.
Seattle starter Yovani Gallardo allowed a bunch of traffic on the bases in walking three and allowing four hits in 4 1/3 innings, but he was stingy when he needed to be in giving up just a pair of runs.
After allowing a pair of singles to start the first, Gallardo limited the damage to one run thanks in part to getting David Peralta to hit into a double play.
"I felt good," said Gallardo, whose previous start was for Mexico in the World Baseball Classic. "I was moving the ball around pretty good, mixing all my pitches, and I think I was able to get some weak contact. I think it's always a positive sign. It's what you want to see."
The D-backs scored three runs in the eighth thanks to an RBI single by Ronnie Freeman and a two-run single by Jake Goebbert.
Mariners up next: The Mariners will stay in Peoria for a home game against the Giants on Saturday at 1:10 p.m. PT on MLB.TV. Right-hander Hisashi Iwakuma will get the start for Seattle and is scheduled to be followed by relievers Nick Vincent and James Pazos.
D-backs up next: The D-backs take a break from Cactus League competition Saturday and will play host to the Netherlands' World Baseball Classic team. Zack Greinke will start for the D-backs in the game which begins at 1:10 p.m. MST and can be seen on MLB.TV.
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