Why Shane Greene's Success Might Be Sustainable

While it is dangerous to put much stock into a small sample size, Shane Greene's granular pitching stats suggest his strong start to his career is not a fluke.

If he is still available in your fantasy baseball league, you might want to join the growing number of people who own Shane Greene.

While he was nearly universally available before of the season, the Detroit righty is now owned in more than half of all Yahoo leagues and saw his ownership increase by 27% on Tuesday alone.

This could very easily be read as an overreaction to two starts -- even if both were very strong -- but Greene's peripherals and swinging strike rates suggest there may be something more here.

The 26-year-old righty was hardly a heralded prospect and was a 15th-round pick by the Yankees in 2009. He did little to raise his profile in the minor leagues, posting a 4.39 ERA, while striking out 7.8 and walking 3.5 batters per nine in 562 minor league innings.

He was a pleasant surprise, though, for the Yankees in his big league debut last season, posting a 3.78 ERA (96 ERA-) to go along with a 95 FIP- and 90 xFIP- in 78.2 innings. He struck out 9.3 batters per nine (23.5% of all batters faced) and had one of the highest groundball rates in the Majors (50.2% per FanGraphs, which would have been 22nd in the Majors had he thrown enough innings to qualify).

Greene was traded to Detroit this offseason, and due in part to the average minor league stats, the projections were generally bearish on him (Steamer, for example, projected him to post a 4.41 ERA this year).

That said, he has picked up 2015 where he left off last year, pitching eight innings in both of his starts, without allowing an earned run in either. In these 16 innings, he has allowed seven hits, one walk, and one unearned run while striking out eight.

It would be foolish to blow two starts out of proportion, but a closer look at his numbers from both this year and last suggest Greene may be more than a small-sample size fluke.

Using the Right Tools

Since we’re talking about fewer than 95 major league innings, we have to be careful as to what stats we use to analyze Greene.

Greene’s career big league ERA is 3.14, but there is so much that goes into run prevention that is beyond the pitcher’s control, like batting average on balls in play (BABIP), home run per fly ball rate and left-on-base rate (stats that are largely random and tend to regress to the league average over time).

It is encouraging, then, that Greene had success, despite a BABIP (.330), strand rate (74.4%) and home run to fly ball rate (12.7%) that were all slightly higher than the league average.

Plus, unlike his ERA, we can put more stock into Greene’s defense-independent metrics, which (as you know) are more predictive of future success and stabilize much quicker.

Strikeout rate may be the most reliable basic pitching stat, as it has a high-self correlation and stabilizes quickly (it takes about 70 batters faced for past strikeout rate to explain 50% of the variance in future strikeout rate, according to Russell Carleton).

We can speak with some confidence, then, about Greene's strikeout rate, given he fanned 23.5% of the 345 batters he faced in 2014.

His 2.3% home run rate was equal to the American League average, despite playing in a hitter’s park and allowing a high(ish) home run to fly ball rate. His high ground ball rate explains why more balls didn’t leave the park, and like strikeouts, ground ball and fly ball rates are reliable statistics.

Carleton found that ground ball rate stabilizes after 70 balls in play, while Greene’s opponents put 568 balls in play last season. He also worked the ball down in the zone at a high frequency, as you can see on his heat map at Brooks Baseball.

His 8.4% walk rate was worse than average, but overall, his defense-independent numbers were strong in his rookie season.

Missing Bats

As mentioned, despite strikeout rate’s reliability, the projection systems aren’t buying Greene, considering that he struck out more than a batter per inning in just one season during his minor league career (his 2010 stint with the Single-A Charleston RiverDogs).

It is fair to expect regression from his 23.5% strikeout rate, but based on how he got these strikeouts, there is also reason to believe it is sustainable.

Swinging strikes per strike percentage (or whiff rate) has a very high correlation with both past strikeouts and future strikeouts, as Mike Podhorzer of FanGraphs and Blake Murphy of Beyond the Boxscore have found.

The advantage to looking at these numbers is that sample size is less of an issue than other stats, given that they involve individual pitches, rather than plate appearances, innings or games.

While Podhorzer found that looking, swinging, and foul strike rates are all fairly consistent over time, swinging strike rate has both the highest self-correlation and correlation with strikeout rate.

Greene’s swinging strike rate was 17.5%, which was 20th in the American League among pitchers who threw at least 1,300 pitches, according to Baseball-Reference.

He also excelled in terms of whiffs per swing, which Murphy found to have an even higher correlation with strikeout rate than swinging strike rate. When he combined whiffs per swing with fastball velocity, he found that the resulting number predicted future strikeouts even better than the previous season’s strikeout rate (no small feat, given strikeout rate’s comparative reliability).

Greene was 28th in the Majors in whiffs per swing (among pitchers who threw at least 1000 pitches), according to Baseball Prospectus, and his 93.5 fastball velocity was above the big league average of 92.1 (per FanGraphs’ PITCHf/x data).

Plugging these numbers into Murphy’s formula, and we see that Greene posted an expected strikeout rate of 24.2% last season, in line with (and, as you can see, slightly higher than) his actual 23.5% strikeout rate.

Strong Start to 2015

Greene has continued to show promise in terms of these pitching stats.

He has struck out just 14.8% of the 54 batters he has faced this year, but has only walked one batter, and continues to generate a high rate of swinging strikes.

In his season debut against Minnesota, he posted a swinging strike rate of 20%, and generated 13 whiffs on 43 swings (a 30.2% rate), per Brooks Baseball.

Tuesday against the Pirates, he generated only seven whiffs on 42 swings (16.7%), but on the season, his whiff to swing rate is 23.5% (which would have still ranked in the top-50 in the Majors last year).

His groundout rate was an atypical 36.4% in his season debut but an especially Greene-like 60.9% on Tuesday.

Plugging his 2015 whiff rate and fastball velocity (93.92) into Murphy’s formula, and Greene has an expected strikeout rate of 23.1%. So with some better sequencing, his strikeout rate should increase going forward.

Considering his impressive looking defense-independent metrics and granular pitching rates, Greene could be an excellent low-risk, high-reward fantasy option (if he hasn’t already been scooped up in your league).