You could be forgiven for thinking that Ketel “One” Marte is older than 23. After all, he’s been around for a while. Marte, hailing from the Dominican Republic, signed with the Seattle Mariners as an international free agent at the age of 16 and made his professional debut in 2012 as an 18-year old. He spent the next four years traversing the Mariners minor league ladder before hitting a respectable .283 in his 219 at bat MLB debut in 2015.
Marte opened the 2016 season at Seattle’s starting shortstop, however a combination of poor performance and injuries resulted in a middling .259 / .287 / .323 batting line and 66 wRC+. With the luster wiped off the once tantalizing prospect, Seattle dealt Marte to Arizona in the offseason along with pitcher Taijuan Walker in return for shortstop Jean Segura and outfielder Mitch Haniger. Walker and Segura were the focal points of the transaction, while baseball pundits salivated about the upside of Haniger. But Marte’s inclusion was largely lost in the shuffle.
Back to the minors
With several incumbent options at shortstop, including slick-fielding Nick Ahmed and the versatile Chris Owings, Marte didn’t have an immediate place on Arizona’s roster and was sent to the AAA Reno Aces to start the season. While he undoubtedly benefited from Reno’s offense-friendly scoring environment, Marte exceeded expectations, hitting .338 over 70 games, good for the second best batting average in the Pacific Coast League among players under 25. His elite plate discipline, evidenced by a 7.4% walk rate, 10.1% strikeout rate and 0.74 walk to strikeout rate, ranked third among players under 25.
Marte’s breakout did not go unnoticed, however the surprise Diamondbacks couldn’t call him up since Owings, Ahmed and Brandon Drury were all covering the middle infield positions with aplomb with the big club. It took a Nick Ahmed wrist fracture in late June for Marte to get his chance, and now Chris Owings is out for two months with a fractured finger as well. One man’s tragedy is another’s opportunity, and unfortunately for Ahmed, it looks like Marte might be Arizona’s shortstop of the future.
A different type of hitter
Prior to this season, Marte never displayed much power, in the minors or the majors. His strong MLB debut was built on solid plate discipline skills as well as a strong batting average, fueled by an unsustainable .341 batting average on balls in play (BABIP). 2016 was an unmitigated disaster, as Marte’s patience at the plate evaporated and his BABIP regressed to more normal levels.
Marte has regained his plate discipline in 2017, however the rest of his profile looks markedly different. A .500 slugging percentage and .258 isolated slugging rate are by far career highs, while his BABIP is at a career low of .245. Ketel One looks more like a power hitter this time around. Of course, 75 plate appearances is a scant sample size, so we need to dig into the numbers further to see if this is the result of random variance or something real.
In 2015 and 2016 Marte’s batted profile matched up with the general perception of him as a slap hitter. Groundball rates north of 50% and flyball rates south of 30%. Most of his batted ball authority was of the soft to medium variety. He was a player that opposing pitchers could attack without much fear.
Thus far in 2017 Marte brings a much more balanced approach. He’s cut his groundball rate from 52.0% to 39.6% and increased his flyball rate to 35.8%, lowering his groundball to flyball ratio by almost 50% from 2.0 to 1.1.
More balls in the air means more opportunity to hit for power, but only if the balls in the air are hit hard. Luckily Marte is doing that as well. He’s significantly cut down on his infield fly balls and increased his hard contact rate from the low 20%s to 34.0%. And while the sample size is still small in 2017, looking at Marte’s rolling 30-game average shows that he’s never experienced this type of combined surge in flyball and hard hit rate.
Let’s get a bit more in-depth
So we know Marte is hitting more balls in the air and he’s hitting balls harder in general. But what is he doing exactly on those flyballs and line drives? Luckily Fangraphs’ splits tool is a terrific feature for this type of forensic research.
It’s not enough to simply hit more flyballs and line drives. If a player wants to inflict maximum damage, he should hit those balls hard and pull them more (unless you’re a psycho like Aaron Judge who can flick balls to second deck opposite field with ease). Marte is doing that in spades, increasing his pull rate on flyballs from 8.9% in 2015 to 52.6% in 2017. He’s also almost doubled his flyball hard hit rate in the same span, going from 22.2% to 42.1%. And not surprisingly, Marte’s slug rate and wRC+ on flyballs has gone berserk in the process.
It’s a similar story on line drives. Marte’s hard hit rate has increased from 32.4% to 53.8% over the last two years, while his pull rate went up from 26.7% in 2016 to 46.2% this season. But there’s hidden upside here. Marte’s BABIP on line drives in 2015 and 2016 was roughly league average around the .670 mark, but it’s down to .462 this season, which would actually be the worst result in the majors if he had enough plate appearances to qualify. Given that Marte’s hitting line drives harder than he ever has, and that his 53.8% line drive hard hit rate ranks as above average, I suspect he’ll be garnering more line drive hits shortly.
Wrapping it up
What have we learned? The 23-year old Marte had a banner year in AAA and is hitting the ball harder than ever before in his 75 MLB plate appearances this season. His .500 slugging rate and .258 isolated slugging percentage are easily career highs. He’s hitting more flyballs and line drives, and hitting those flyballs and line drives harder than ever before. The improvements in Marte’s batted ball profile recall the changes behind Scooter Gennett’s career season with the Reds. Marte has a clear path to at bats for the rest of the season with Nick Ahmed’s wrist fracture and Chris Owing’s finger fracture, so act now in fantasy leagues before it’s too late.