What the Mariners get in new arm Nate Karns

Jerry Dipoto completed his first trade as the General Manager of the Seattle Mariners on Thursday. It was a six-player deal with the Tampa Bay Rays. One of the pieces coming to the M’s is an immediate impact– starter Nate Karns.

Karns, who stands 6’3″ tall and turns 28 years old later this month, has made 31 career MLB starts. He broke into the big leagues in 2013 with the Nationals making three starts with a 7.50 ERA over 12 innings. In 2014, after being traded to the Tampa Bay Rays, he started two games and showed improvement with a 4.50 ERA in 12 innings. Several injuries to the Rays’ staff this past season led to 26 starts and a 3.67 ERA. As we all know, ERA doesn’t tell the whole story so let’s dig deeper into the M’s new starter.

It’s hard to compare his time in the majors as the first two stints were very small sample sizes. So let’s start by comparing his 2014 season in Triple-A for the Durham Bulls versus this past season in Tampa. He threw 145.1 innings in 2014 for Durham while tossing 147 in the majors this season. Some of the areas Karns really improved were his walks per 9 innings and batting average against. His BB/9 rate was 3.43 in 2015, down significantly from the 3.84 he posted in Durham. One thing I did find interesting was his average velocity, which was down about 1.5 MPH (93.2 – 91.6) from his 2014 appearance in the big leagues. This could be a sign that he might have been working on his command and felt if he took a mile or two off his fastball it would help. His batting average against was .254 in 2014 compared to .236 in 2015. Karns saw more ground balls hit (41.9%) against him this past season than fly balls (36.5%).

In two starts against the Los Angeles Angels in 2015, Karns went 10.2 innings giving up eight earned runs and three home runs. Then Angels’ GM, Dipoto, must have seen enough in his whole body of work to want to bring him to Seattle.

Here are the 2015 month-by-month totals for Karns.


5 GS/28 IP/15 ER/16 BB/25 K


5 GS/28.2IP/6 ER/8 BB/28 K


6 GS/34 IP/12 ER/12 BB/31 K


4 GS/24 IP/10 ER/4 BB/22 K


6 GS/29 IP/16 ER/15 BB/35 K

The Rays basically shut down Karns in September after a rough August where he was said to be battling some fatigue.

Karns is a three-pitch pitcher throwing a four-seam fastball 58.1% of the time in 2015, curveball (28.7%) and change-up (12.5%). Giving up home runs has been a problem area as he gave up 8 home runs over his first 24 career innings and gave up 19 this past season. Pitcher-friendly Safeco Field should help keep home run numbers down in 2016.

Nathan Alan Karns figures to be penciled into the rotation behind Felix Hernandez and Taijuan Walker. The question marks will be James Paxton and possibly Hisashi Iwakuma. Paxton is coming off a finger injury that cost him most of 2015 and Iwakuma will have to accept a qualifying offer or re-sign to be in an M’s uniform next season.

A big plus for the M’s is that Karns is under team control for another two years and won’t be arbitration-eligible until 2018. The Texas native has never pitched at Safeco Field but that will certainly change in 2016.

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