A Ray of sunshine in Arizona

The Arizona Diamondbacks have quietly been one of the most surprising teams in baseball. They currently find themselves just two games out of first place, and if the season ended today they would make their first playoff appearance since 2011. This is a far cry from the team that felt like a punchline for much of the last three seasons. What’s led to this turnaround?

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The Diamondbacks and Rockies are right in the mix in the National League. Which club is more likely to sustain it?

The starting rotation has had a major hand in Arizona’s success. Three of the Diamondbacks regular starters are having above average seasons by ERA+ (Zack Greinke, Robbie Ray, and Taijuan Walker). The team has also received solid production from a handful of pitchers who have made spot starts.

Ray is the pitcher who stands out from the trio mentioned above. Among qualified starters, he has the ninth-best ERA (2.85) and third-best strikeout rate (31.4 percent). There was buzz prior to the season that Ray was a breakout candidate, but few could have predicted this level of success.

This leads to the obvious question: why has Ray been so productive?

He’s Changed His Pitch Mix

There have been a few obvious changes to Ray’s pitch mix this year. In 2016, Ray depended heavily on his fastball, sinker, and slider. By the end of the season, his fastball and slider had become his predominant pitches. Ryan Romano of Beyond the Box Score wrote about Ray’s slider earlier this season.

However, in 2017 Ray is incorporating a curveball into his arsenal. It’s been his second most used pitch since April. He’s continued to use his slider 15-20 percent of the time, and this development has given him three quality pitches to attack hitters.

The following chart shows how Ray’s pitch usage has changed throughout his career.

Brooks Baseball

Even though he’s heavily relied on his curveball, Ray is still using his fastball and slider as his primary strikeout pitches. He’s throwing his fastball 50 percent and his slider 31 percent of the time when he has two strikes on a hitter. His curveball is helping him keep hitters off balance, but when it’s time to close the door he’s returning to his two favorite pitches.

He’s Getting Batters to Miss More Pitches Outside the Zone

Another reason for Ray’s increased strikeout rate is the fact that he’s getting hitters to swing and miss at pitches out of the zone at a higher rate. Last year, Ray’s O-Contact rate sat at 58.5 percent. That’s close to his career mark of 61.3 percent. However, this season batters are only making contact on 46.5 percent of Ray’s pitches thrown out of the zone.

The largest cluster of those misses has been down-and-in to right-handed hitters. He’s also had success elevating his fastball in the zone. It sounds simple, but Ray’s mid-90s fastball and two breaking pitches are making it difficult for batters late in counts. He’s willing to rely on any of those pitches, and that makes it tough for hitters to know what to expect. All three pitches have a positive rating by FanGraphs Pitch Values.

Brooks Baseball

He’s Gotten a Little Lucky

Robbie Ray has been good this season, but he’s also been a little lucky. The most obvious case of this is his .251 BABIP through 12 starts. That’s the 11th-lowest rate among qualified starters, and it’s well below his career .325 BABIP. This result is even more surprising given that his hard-hit rate is up just over six points this season (42.9 percent). It’s difficult to count on his BABIP remaining this low.

That’s not the only instance of good fortune Ray has encountered. Currently, he’s stranding 81 percent of batters who reach base. Again, this is noticeably different from his career LOB% of 71.2 percent. FanGraphs notes in their explanation of LOB% why this result is unlikely to hold.

“Most pitchers have LOB%s around league average (which is approximately 70-72%, depending upon the season), and pitchers that deviate from that average tend to see their numbers regress towards average in the future.”

To be fair, the article also mentions that high strikeout pitchers are more likely to run a high LOB% than other pitchers. The fact that Ray has seen a bump to his K% and LOB% simultaneously might not be a coincidence.

There’s one other factor to consider with Ray’s results. He’s recently benefited from a fairly light schedule. Tom Whalen of Fantasy Pros highlights that Ray’s past five starts have come against Pittsburgh (x2), San Diego, and Milwaukee. In three of those five starts, Ray went at least seven innings with zero runs allowed. As Arizona’s opponents get more difficult, it’s possible Ray could see some changes to his results.

Robbie Ray has been great so far this season. Will he remain this good? As of now, the evidence is mixed. But if you’re a Diamondbacks fan you have to be happy with the development you’ve seen from this 25-year-old starter.

All stats are current through June 11.

Eric Roseberry is a writer for Beyond the Box Score. You can follow him on Twitter at @ericroseberry. He also writes for Baseball Prospectus and Red Reporter.