40 in 40: D.J. Peterson

In his brief, four-year pro career, D.J. Peterson has been every kind of prospect in the book.

From 2013-2014 he was the big name prospect, comfortably landing on Top-100 prospect lists and the daydreams of Mariners fans longing for a solidified first base position. Peterson had journeyed to Low-A Everett, Class-A Clinton, High-A High Desert, and Double-A Jackson, and none represented much of a challenge for the New Mexico product. His lowest wRC+ during the span was a 126 mark in Jackson. His second-lowest was 154 (High Desert). He was a hitting machine. The future was bright. The Mariners had their first baseman.

In 2015, Peterson became a broken, busted prospect. Mechanically, his swing failed him on nearly every level. The once sweet-swinging first baseman had become an extreme pull-happy hitter, his front half flying open in a violent and twisted manner on nearly every pitch. The patience went away with the new approach. Entering the month of July, he was hitting .211/.289/.337 at the very same level he had just performed well against the year before. In just a few months, Peterson went from top prospect to an afterthought.

2016 saw Peterson rebuild his stock and turn himself into a bounceback prospect, even if the depth label he currently sports is a far cry from what he was projected to be a couple years ago. I dove into his changes a bit earlier this year, but a quick summary of what helped him get back on track:

• A mechanical overhaul of his swing, including a quieter and more upright stance
• Using more of the field, specifically staying through the middle
• An emphasis on being more selective with pitches

It all sounds fairly generic, but they were parts of the game Peterson got away from in 2015, and they were all parts of the game he excelled at in 2016. His shine wore off a bit during his time in Tacoma, where he hit just .253/.307/.438 before an injury ended his season, but it was a positive season for Peterson overall.

The Mariners rewarded his success with a spot on the 40-man roster, a decision to hang on to him (so far) in an offseason where they’ve traded every prospect with two ears, a heart, and a baseball mitt, and a vote of confidence that his “best baseball is ahead of him”.

2017 will be the ultimate make or break year for D.J. Peterson: Seattle Mariner. A big year could propel him back into the team’s longterm plans in some capacity. A down year will have him looking like one of the more likely 40-man casualties in the event of a vast amount of offseason moves.

His tale will begin in Tacoma, where he’ll get his first long look against Triple-A competition (192 PA in ‘16, 14 PA in ‘15). With the sudden influx of athletic, MLB-ready outfielders on the Mariners roster (and theoretically Triple-A Tacoma’s roster), it’s hard to see much carryover with the late season idea to work him out in a corner outfield spot. That being said, I still feel we’ll see a first base-tethered Peterson in Seattle at some point in 2017, be it due to injuries on the 25-man roster or simply as a right-handed bench bat down the stretch.

Go get ‘em, D.J..