What's wrong with the Mariners prospect DJ Peterson?

Heading into the 2015 season, many people had high hopes for the Seattle Mariners. They were seen to be the team to beat in the American League West. Despite not having the deepest farm system, it was viewed as one with a few impact players coming up the pipeline that would help sustain that success.

It has been anything but that. The Mariners on the big league level are an abysmal 34-42 with one of the worst offenses in all of baseball. Their top prospects have been plagued with injury or have been severely disappointing. One of those under-performing prospects is D.J. Peterson.

Peterson was the Mariners 12th overall draft pick in 2013. Quite frighteningly, Peterson’s impressive debut season was cut short when he took a ball in his face and broke his jaw.

The 23-year old corner infielder would show no ill effects in 2014, as he bounced back to have a monster season. Peterson slashed .297/.360/.552 with 31 home runs and 111 RBI over High-A and Double-A. Gaining both a Futures Game invite and being named to the Arizona Fall League Future Stars team, Peterson skyrocketed up Minor League Baseball’s prospect list heading into 2015.

2015 has been a nightmare thus far for Peterson. He entered the season as the No. 2 prospect in the Mariners system and was a consensus top 50 prospect in Minor League baseball. Something is clearly not right.

One does not want to make excuses, but perhaps Peterson saw the finish line too soon. Peterson saw a prime opportunity this season, especially once fellow mashers like Kris Bryant — who had minimal experience at Triple-A — and Joey Gallo — who like Peterson, never saw a Triple-A pitch — made the successful jump to the big leagues.

The aforementioned struggling Mariners offense is last in the American League in batting average, runs and RBI. Peterson, who’s defense is questionable at best at his original position of third base, has been transitioning across the infield. Had Peterson been putting up numbers anywhere close to what he did last year, he may have gotten a chance like so many other prospects have this season.

Logan Morrison is doing what Logan Morrison does, which is playing adequate first base. Despite putting together a solid season at Triple-A, the Mariners seemingly still have little faith in Jesus Montero, as they went out and acquired Mark Trumbo. Trumbo is 10-for-73 since joining the Mariners, good for a .137 batting average, and has hit just one home run. The door is wide open for a young buck to provide a spark for a struggling offense.

Peterson’s numbers aren’t simply off of last year’s mark, they are way down. His home run rate has dropped drastically as his strikeout rate has worsened as well. Last year with the Single-A High Desert Mavericks, Peterson hit a home run every 15.2 at bats. His promotion to Double-A saw an ever so slight drop off to a home run every 17.1 at bats.

This season, Peterson is hitting a home run once every 52.2 at bats. He now has five home runs on the season. Normally it isn’t always fair to use home runs as a gauge to judge a player, but with subpar fielding grades and average hitting grades, power was Peterson’s path to the big leagues. That power is failing him. He hadn’t hit a home run in his last ten games until Monday night (when he hit his fifth) and has only four extra base hits altogether since his last home run.

Peterson has always had struggles with strikeout rates, but he is striking out even more often this season. Last year in his breakout campaign he struck out once every 4.71 at bats, or 21-percent of the time. This year he is striking out once every 4.34 at bats, or 23-percent of the time. That’s a big enough spike to be concerned coming off of last season. His batting average on balls in play is also at a career worst .266, so maybe he is a victim of some bad luck as well.

Again, not to make excuses, but perhaps Peterson is struggling as he focuses on his transition from the hot corner to first base. Peterson has actually been playing first base reasonably well, so the argument could be made that he has been so determined in his career change that he has lost focus on his hitting.

By no means am I insinuating that Peterson is a bust, but it is certainly time to be concerned if this is a slump or a digression. Seeing that he has not hit this poorly in his short professional career, I would side with the slump factor, albeit a very long one.

Many felt that by mid-season, Peterson would be Triple-A bound, where he would be able to tear the cover off the ball in the Pacific Coast League. Several envisioned a September call-up. Right now, both of those aspirations need to be put on hold while Peterson figures out what’s wrong, bumping his arrival date well into the 2016 season.