Tacoma Rainiers

Seattle Mariners prospect D.J. Peterson starting to show signs of snapping out of slump

The Tacoma Rainiers carried a six-game losing streak into Saturday night’s game against Sacramento, and coincidence or not, the streak started when first baseman Jesus Montero was recalled by Seattle.

Without a first baseman on the Triple-A roster, it makes sense to check in on how top prospect D.J. Peterson is faring at Double-A Jackson.

Peterson, 23, was ranked the Mariners’ top prospect by Baseball Prospectus before the season. Baseball America had him ranked No. 2 overall.

A corner infielder, Peterson got off to a woeful start at Jackson, with a slump that lasted several months. When the Southern League All-Star break began June 21, Peterson was batting .207 with four homers and 31 RBI — not exactly the numbers the Mariners were looking for from their top power-hitting prospect, who was coming off a combined 31-homer season in 2014.

But Peterson’s performance has improved recently. In 21 games since the break, he has hit .265 with two homers and nine RBIs while posting a .700 OPS.

Those numbers don’t scream “power prospect,” but they show at least some improvement.

After hitting a grand slam on Thursday, Peterson told MiLB.com that he watched himself on video to help fix some flaws in his swing.

“I had to figure out where I’d been with my load, where my hands were, to get back to where I was then,” he said. “I’ve just been trying to find my swing, where it was. I think the last couple months ... I’m starting to feel it a little better, find my swing.”


Mariners outfield prospect Ian Miller missed most of last season with a back injury, but the speedster is making a quick climb up the minor league ladder.

A 14th-round draft pick in 2013 out of Wagner University, Miller was selected primarily for his speed.

He was stealing bases at a rapid clip, going 16 for 18 at Single-A Clinton last year before the back injury ended his season on June 5.

This year he opened the season with Advanced-A Bakersfield and hit .296 with 21 steals in 39 games. That prompted an early promotion to Jackson, where he has continued the pace with 15 steals in his first 42 games. He leads the organization with 36 steals.

Miller is working to improve his on-base skills to further take advantage of his speed. A left-handed hitter, Miller is batting .242 with a .310 on-base percentage for Jackson.

Mike Curto is the radio broadcaster for the Tacoma Rainiers.