Sonny Gray for Ace

In 12 appearances including 10 starts, Sonny Gray did all the things you want to see out of a potential fantasy workhorse. He struck out over a batter per inning (9.42 K/9), kept the walk rate under control (2.81 BB/9), and threw ground balls over 50 percent of the time, all while wielding a 93 mph fastball. His ERA, FIP, and xFIP all stood below 3.00, which is about as sure a sign of dominance as there can be.

If there’s anything to complain about with the 23-year-old, it’s that he has such a short track record as a professional. Before his 64 inning cup of tea last season, Gray threw just 292 minor league innings over about two seasons. He threw just 22 innings in 2011 and turned in a lackluster performance in 2012. That included a strikeout rate of 5.90 K/9, a K/BB ratio of 1.70, and a 4.14 ERA. His minor league numbers saw stark improvement in 2013 and matched those he put up in his short MLB debut.

His major league data contain one odd piece of information – opposing hitters were disinclined to swing at Gray’s pitches. They offered at just 22.8 percent of pitches outside the strike zone and 58.9 percent of pitches within the zone. For comparison, the league averages were 31 percent O-Swing and 65.5 percent Z-Swing.

I looked at Danny Salazar and Michael Wacha to see if this had something to do with his short track record in the majors. All three pitchers received a similar amount of major league experience last year and featured comparable peripherals. However, Wacha saw typical swing rates while Salazar induced swings at an above average rate. It’s possible that we’re looking at a small sample fluctuation.

His O-Swing rate was actually the lowest among all pitchers with 60 innings last season, including relievers. His Z-Swing was sixth lowest, which combined to give him the lowest overall swing rate. Perhaps we can tease out some explanation from his PITCHf/x data.

Gray PU

He features a deep six pitch repertoire although he only uses four pitches with regularity. My first thought was that the slider and cut fastball were actually the same pitch, but they feature a five mph velocity gap and move differently. Gray has a standard approach, he likes to get ahead with the hard stuff then bring in the curve ball. The four seam fastball and curve ball were his best pitches last season, although the sample size involved is too small to get excited. Despite excellent numbers with his curve ball, the whiff rate on the pitch is merely good at 15 percent.

Gray RA

My suspicion is that he does a good job of working on the edges of the strike zone. Bill Petti and Jeff Zimmerman found that pitching to the edges of the strike zone improves overall performance while building their Edge% statistic. My hypothesis is that Gray does this particularly well. Combined with his deep repertoire, that could explain his low swing rates. I don’t have access to Edge% data on Gray, so I have overlaid his pitch map with two boxes that approximate the zone used by Petti and Zimmerman.

Gray Edge

A good Edge% is around 20 percent (between the 75th and 90th percentile) and it certainly looks like Gray has reached that threshold (I recommend zooming in on the chart for full effect). I also split his season into thirds since we’re only using the eye test. It looks similar for each smaller chunk of data. Gray also does a great job of hugging the bottom of the strike zone, which isn’t part of Edge%. That’s a big reason why his ground ball rate is so good.

Assuming his command and control hold up over the offseason, these findings bode very well for Gray. If I had to pick a single young pitcher in the game who has the best chance to become a Cliff Lee quality ace, it would be Gray. But don’t get too excited, he still has much to prove since the league did not have much time to adjust to him last season.

He should be a fairly low injury risk for a pitcher, which is to say that there’s about a 30 percent chance he will land on the disabled list. He did suffer a quiet thumb injury in his final postseason appearance against the Tigers. The injury – which was to his glove hand – required offseason surgery. That shouldn’t affect his overall health profile.

He didn’t pitch enough to land on Zach Sander’s list, but he was probably worth roughly $6 in his limited time. Next season projects to around $15 of value. His price tag in drafts is unknown. He outdueled Justin Verlander once in the postseason, which is the kind of exploit that brings attention on a player. Still, I expect owners to target him as a good third tier pitcher (roughly $9 last season) whereas I’m inclined to target him around where James Shields went (about $14). In snake drafts, I expect name brand players like Jon Lester and Tim Lincecum to go off the board before Gray, but I would jump on Gray before either veteran – at least I would if my drafts were held today.


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Nick J
Nick J

Good article, I’d enjoy to see more of the edge% in following articles. That statistic could be the deciding factor on which young flame thrower to roster, and will show why guys, such as Doolittle with 95+ get tapped from time to time. How would you rank Salazar, Wacha, Grey? I would take Salazar first, because I love his fastball, but Wacha and Grey are so damn similar its a toss up for me.