Why the Royals chose Nathan Karns as their fifth starter

Royals manager Ned Yost informed the media Monday that Nathan Karns will be named the team’s fifth starter, as one of the first significant roster moves of spring training for any team.

After the tragic death of young star Yordano Ventura in late January, the Royals found themselves in dire need of starting pitching depth. They signed both Jason Hammel and Travis Wood in February, with the latter expected to compete for the fifth spot in the rotation. And while Karns was acquired from the Mariners weeks prior to Ventura’s passing, he too gained increased importance in the battle for the roster spot. After a strong spring thus far, Karns will open the season as Kansas City’s No. 5.

The skinny on Nathan Karns

The 29-year-old Karns was drafted back in 2009, when the Nationals took him with their 12th-round pick (352nd overall) out of Texas Tech University.

He was traded to the Rays for three players in 2013, but did not truly begin his MLB career until he joined the rotation in 2015. That season, Karns was solid, posting a 7-5 record with a 3.67 ERA and a 145-56 K/BB ratio over 147 innings pitched. His peripherals were respectable enough to post a 4.09 FIP, a 3.90 xFIP and 1.5 fWAR.

Karns was dealt to the Mariners at the end of the 2015 season, and his results last year were not nearly as strong. A 5.15 ERA over 94 ¹⁄₃ innings is never good, although his FIP (4.05) and xFIP (4.23) tell a different story with regards to his effectiveness. Karns also spent time in the bullpen, and his poor showing in that role (13 ER over 13 ¹⁄₃ IP) belied his more satisfactory numbers as a starter (4.56 ERA in 81 IP).

From a scouting perspective, Karns has a solid fastball that can reach up to 97 mph, but his ability to strike out batters at a high clip comes from a knuckle-curve that’s among the best in the Major Leagues. Over the last two seasons, Karns’ curveball ranks eighth in the Major Leagues in weighted runs above average at 11.8. His curve ranks higher than those of Madison Bumgarner, Jake Arrieta, and Jose Quintana. Of the 351 plate appearances to end with Karns’ knuckle-curve, 117 have been a strikeout. That’s a ridiculous 33.3 percent.

Spring training stats don’t matter, but Karns’ strikeout-to-walk rate this Spring is certainly a promising sign and could be one of the reasons why the Royals decided to give him a shot in the rotation. He’s made five starts thus far, tossing 17 innings with a 23-5 K/BB ratio. A 4.76 ERA isn’t phenomenal, but not only is it a small sample size, it’s (again) spring training.

Projecting Nathan Karns

Steamer and ZiPS both have their projections available for Karns’ 2017 season, and the only real thing that differs between them is the amount of innings they think he’ll throws and the counting stats that come along with it. FanGraphs’ depth charts, the third projection system here, is a combination of ZiPS and Steamer (eliminating some bias there) with playing time allocated by the site’s staff.

All three projection systems tend to agree on the type of player that Karns is. He’s a mid-4 ERA guy who will average around a strikeout per inning with decent control. And, for a fifth starter, it’s hard to argue with results like that. Karns can easily be the innings-eater that the Royals signed him to be.

But, it’s also possible for Karns to see some growth. With such a devastating curveball and the fastball velocity that he has, Karns’ upside is still pretty big. The lack of a good third offering definitely limits his potential, and that’s probably why he was never a front-line prospect to ever begin with. Still, though, better fastball control, and Karns’ abilities go from those of a No. 5 starter to those of a No. 2 or 3.

Comparing Karns to the Royals’ other options

Karns beat out Travis Wood and Chris Young to earn the Royals’ No. 5 job, and it’s really not hard to see why.

Young is 37 years old, and threw only 88 ²⁄₃ innings last season, none of which were all that pretty to watch. He posted a 6.19 ERA and a 94-43 strikeout-to-walk ratio in his 34 games (13 starts). He uncharacteristically struck out a lot of hitters, but his control was well below his already-high career average. FanGraphs did not like his season at all, pegging him at 1.2 wins below replacement level, or -1.2 fWAR. With declining velocity and poor results, it probably was a stretch to see Young in the Royals’ rotation, although he might fit in the bullpen.

Wood, on the other hand, is still pretty young at age 30, and Kansas City did invest $12 million to sign him, likely under the intention that he would start for them. The problem is, though, Wood has not exclusively started since 2014, and that year he posted a 5.03 ERA and a 4.38 FIP over 173 ²⁄₃ innings. He also does not carry the same amounts of upside that Karns has. Plus, Wood is also a pretty solid left-handed matchup guy out of the bullpen. Southpaws hit just .128 off Wood last year, so having him as a LOOGY isn’t a liability.

To sum it all up, the Royals went with Karns because, at the very least, he will eat innings at an effective rate. That’s really all you can ask for out of a fifth starter. But with some improvements that they hope he’ll make, Karns could be a very good pitcher, something that his two competitors — Wood and Young — both lacked. When upside is involved, it’s always a good idea to go with the player who could provide the biggest reward going forward. That led the Royals to Karns, who could be a lottery ticket for them in 2017.