Breaking Down Vidal Nuno’s Debut, Inside the ‘Zona Style

At Inside the ‘Zona, we strive to provide analysis that you can’t get anywhere else. We like to think of ourselves as reflective rather than reactionary. This is not the blog where you go to find knee-jerk reactions or instant commentary on a game-by-game basis. Hopefully, you come here for something more thoughtful. You bookmark this page (please do) so you can learn about your favorite baseball team, the Arizona Diamondbacks, in a different way, one that is based on cutting-edge statistics and logic, instead of the usual hot take commentary.

So, it wouldn’t be right for us to write about Vidal Nuno‘s strong debut by simply mentioning the irony. No, at Inside the ‘Zona, we will try to break it down in a unique way.

It doesn’t take much to realize that Vidal Nuno pitched well in his first Diamondbacks start. He lasted seven innings, allowing zero runs, striking out seven and walking only one. Using GameScore, developed by Bill James, Nuno’s start was the third best for Arizona this season (Josh Collmenter in late May against Cincinnati and Brandon McCarthy in mid-May against Washington were the top two).

For those unfamiliar with GameScore, it is a more advanced way of looking at the quality of a pitcher’s start. We know the metric quality starts exists, but that simply looks at the number of runs allowed over a determined number of innings. GameScore utilizes a plus/minus system to assign points based on a number of factors important to measuring an effective start.

GameScore Formula:

Start with 50 points. Add 1 point for each out recorded, (or 3 points per inning). Add 2 points for each inning completed after the 4th. Add 1 point for each strikeout. Subtract 2 points for each hit allowed. Subtract 4 points for each earned run allowed. Subtract 2 points for each unearned run allowed. Subtract 1 point for each walk.

Nuno’s GameScore of 77 in his D-backs debut was not only the third best of any starter on the team this season, it was Nuno’s highest score in his career; his second best score being 68 in a game he pitched for the Yankees against Boston in June.

Now that we have established what we knew from watching the game – that Nuno pitched really well – we can try to answer the question of why? What, if anything, did Nuno do differently to find such success? Is it a sign of more good to come? Or was it just a fluke?

The first thing that jumps out, looking at Tuesday’s start, is Nuno’s pitch selection. According to Pitch F/X, Nuno threw his four-seam fastball more frequently on Tuesday than any game in his career. He threw the pitch 44% of the time, which is good because according to FanGraphs pitch value calculation, which measures the efficiency of each pitch based on run expectancy, Nuno’s four-seam is his best pitch. He offset the increased usage of the four-seam by throwing less of his two-seam, which happens to be his worst pitch. Pretty simple stuff, then. He threw his best pitch more, and his worst pitch less.

Nuno has five main pitches in his arsenal; he throws a slider, two-seam, curve, occasional change-up, along with the four-seam. Opposing hitters hit well above league against each of his offerings, with the exception of the four-seam and change-up. Both pitches that he threw with high frequency, relative to his typical pitch selection, in his strong debut.

Is it as easy as throwing one pitch more often than another? It is difficult to make too many conclusions about Nuno with such a small sample size over his career. Taking some liberty in doing so, we know that his fly ball rate is high (career 44.4% versus league average of 34.2%), and consequently his ground ball rate is low (career 36.3% compared to league average of 45.3%). Fly balls can turn into extra base hits, and most damaging, home runs, while ground balls may result in singles, but are least harmful. Nuno has suffered from a 12.9% HR/FB rate this season.

Unfortunately, Tuesday’s strong start was not a result of a change in the type of balls put in play. Nuno produced his third least amount of ground balls this season and fifth most fly balls. His line drive percentage, which is a barometer of how hard hitters connected on his pitches, was also his fifth highest on the season. What happened for Nuno in his debut was that a lot of the balls in play that have been falling for hits or sailing for home runs turned into outs. His batting average on balls in play was a miniscule .176.

Now we have painted a bit of a picture. Nuno was effective in his debut by throwing his best pitch at the expense of his worst pitch. In terms of balls in play, his pitch selection didn’t seem to change much, but the results were better. The last point to consider is how he was able to throw strikes and avoid walks. Nuno threw 52.8% of his pitches on Tuesday inside the strike zone, which is a jump above his season average of 46%. On top of throwing a lot of pitches for strikes, Miami hitters were aggressive, swinging at 50.6% of all offerings, again above Nuno’s season average of 44%. The result of more pitches in the zone and aggressive Miami hitting was a respectable K/9 rate of 9.0 and BB/9 rate of 1.29.

It will take a lot more starts like his first one to make the return on Brandon McCarthy feel suitable to D-backs fans. What our analysis shows us is that perhaps Nuno was a bit lucky, keeping fly balls and line drives from turning into base hits and home runs, while taking advantage of an aggressive swinging team in Miami on Tuesday. We can also hope that perhaps an increased use of his four-seam relative to his two-seam produces better results and not just an adjustment by opposing hitters to cancel it out.

Statistics courtesy of FanGraphs and Baseball-Reference.