In 2015, Zack Greinke posted one of the most historic lines in major league history. His 1.66 ERA was the lowest since Greg Maddux (1.63) in 1995. His 0.84 WHIP was the lowest since Pedro Martinez (0.74) in 2000. The natural inclination when a season like this happens is to think that there's no way a player can repeat it.
Upon further review, Maddux's 1.63 was an encore to a 1.56 ERA in 1994. Clayton Kershaw had a sub-1.85 ERA in consecutive years from '13-'14. In other words, sometimes great pitchers spit in the face of natural regression. The question then becomes, how great was Greinke in 2015? That is a tricky question.
A quick glance at FIP (Fielding Independent Pitching) says that Greinke's 2015 was .4 of a run worse than any of the four seasons we've referenced above. In fact, Greinke's 2015 FIP would rank 30th in the last decade. Good, certainly, but not necessarily elite. This discrepancy can be explained by some numbers that were even more historic than Greinke's ERA or WHIP.
Batters hit .229 on balls in play against Greinke in 2015. That wasn't even the lowest in baseball last season (thanks, Marco Estrada), but it was the fourth lowest since 1989. Once they got on base, Greinke stranded them at an 86.5 percent rate. That is the highest mark since the 2000 Martinez season. These numbers all but eliminated small ball, and Greinke also limited the long ball, with a 7.3 percent HR/FB rate (the fourth best in baseball last season).
Maybe you're impressed already, but let's put those numbers together. One pitcher in the past 50 years has posted a BABIP and a strand rate as low as Greinke did in 2015. It was Bob Gibson, in 1968. That was the famed Year of the Pitcher, when the league average BABIP was .268. In 2015 league average was .296. Even Gibson's season isn't really comparable.
Assuming that pitchers have considerably less than 100 percent control over BABIP, strand rate and HR/FB rate, Greinke's fortune last year was unprecedented. All of this is to say "Can Greinke Do It Again?" may be the wrong question.
I believe he can strike out 8.1 batters per nine again and he may even be able to repeat that phenomenal walk rate. Zack Greinke very well may repeat what he did in 2016, but if history is any indicator, it will lead to different results.
Early ADP data suggests Greinke is being drafted as the sixth pitcher off the board around the middle to the end of the third round. His peripherals suggest that is far too early. Unless he strikes out a lot more batters, owners who draft him there are likely to be disappointed by regressing wins, innings and ERA.