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MLB Prospect Review: D.J. Peterson, 3B, Seattle Mariners

The Mariners selected New Mexico third baseman D.J. Peterson with the #12 overall pick in last year's draft, and has been hitting well since signing. Can he stay at third base in the long term, and what could he be for your fantasy team?

Otto Greule Jr

Throughout the minor league season, the prospect staff here at Fake Teams will look at a number of prospects for your fantasy and dynasty teams. Some will be prospects that you'll see this year in the majors, while others are interesting targets in longer term formats. Up today is the Mariners' top draft pick from last year, third baseman D.J. Peterson

The Basics

Bats: Right
Throws: Right
Height: 6'1"
Weight: 190 lbs.
On 40-Man Roster: No 
Protect After: 2016 Season
DOB: 12/31/1991 (Age 22 Season)

His History

Peterson was drafted by the Mariners out of high school in 2010 in the 33rd round, but did not sign despite being offered a well-over-slot deal, and attended the University of New Mexico. A .419/.490/.734 slash line with 17 home runs his sophomore season put him firmly on the map for the first round of the draft, and was viewed as the #10 draft prospect from the college ranks coming into his junior year by Baseball America. Another strong campaign (.408/.520/.807, 18 HR) confirmed that belief, and the Mariners took him with the 12th overall pick. He signed for a slot bonus of $2.75 million shortly after the draft.

He debuted with the Mariners' short-season affiliate in Everett, Washington, and appeared in 29 games before being promoted to full-season Low-A on July 24th. He spent another month with Clinton, but his season ended prematurely after a hit-by-pitch broke his jaw. Across 55 games, Peterson hit .303/.365/.553 with 13 home runs, 20 walks, and 42 strikeouts.

Peterson is currently at High-A High Desert, where he has appeared in 24 games but missed about a week with a strained hamstring. He is hitting .280/.321/.400 with 2 home runs and two stolen bases, and has a hit in 5 of his 6 games since returning from the injury.

The Scouting Report

Hit (AVG): Peterson has the potential to be an above-average hitter. He has shown a natural ability to hit to all fields, generating good bat speed at the plate and making solid contact. He should provide a good batting average (.270+) on a consistent basis, and provide a decent on-base percentage to go with it.

Power (HR, RBI): Peterson has plus power potential, and when combined with his hit tool, could be a 20-25 home run bat with the potential some years for even more. He was considered one of the top power bats in last year's draft, and the power should still translate despite his future home park.

Speed (R, SB): Peterson is considered a below-average runner, and as a result is unlikely to provide more than token value in terms of stolen bases. He should score a solid amount of runs, but these will be driven entirely by his own production and the production of those batting behind him. Think your standard fare power hitter, who can score between 60-80 runs but will never be an elite contributor in that category.

Defense: Defense is the biggest question mark for Peterson, and unfortunately is also what can have the most impact on his value for fantasy owners. He has the arm to play third base, but that's about all. He is viewed as having both below-average range as well as below-average reactions at the hot corner, and a move to first base or a corner outfield spot are extremely likely. Based on the performance so far (9 errors in 97 chances last year, 9 in 40 chances this year), it would not surprise me if that move happened at some point in this season.

When Could He Arrive in the Majors?

Peterson is expected to be a fast mover, and could reach AA before the end of the season. If he does, a debut during the 2015 season isn't out of the realm of possibility. He could be an everyday player by the end of the 2016 season.

What Can He Do for Your Fantasy Team?

The key to his value lies with the positional eligibility. He should be good for a .270-.275 average with 20+ home runs every year, which plays drastically better at third base than at first.


Peterson is a tantalizing name given the power potential he has. It's not out of the question that he could hit as many as 30 home runs in a season some years, while providing a good batting average at a shallow position. However, the risk you're taking on with him is that he ends up a good but not great hitter at first base where there are many more options just like him. We should learn a bit more about him once he reaches AA, but he is an interesting name to watch this year.


Baseball America
Baseball Reference
Baseball Prospectus
The Baseball Cube
MLB Farm
Lookout Landing