The Arizona Diamondbacks invested heavily in their starting rotation this offseason. They traded for Shelby Miller, signed Zack Greinke and had Patrick Corbin returning healthy after only making 16 starts last season. It looked like they had a formidable trio atop their rotation and could potentially challenge for a playoff spot. So far, that has not worked out, and the Diamondbacks find themselves only a half game out of last place in the NL West.
Their pitching is the big reason behind their struggles. They currently have a minus-25 run differential and have allowed 155 runs, bad enough for third most in the National League. Not a single starting pitcher has an ERA under 4.00, as Rubby De La Rosa is currently pacing the staff with a 4.60 ERA.
Greinke has allowed a whopping 47 hits in 37.2 innings, five of which have been home runs though they did come in two games. He allowed 14 home runs all of last year and has averaged only 15.4 home runs allowed throughout his career. He is currently on pace to allow 26.66 home runs over 32 starts or 29.1 over 35. There is some hope that Greinke will get himself back on track. He did strike out eight in seven innings in his last start, though he also allowed two walks and eight hits.
The biggest concern for the Diamondbacks has to be Miller. He is one of the worst starting pitchers in baseball this year. In 23.1 innings he has allowed 27 hits, 22 earned runs and has walked as many as he has struck out, 19. His ERA currently sits at 8.49, and he is on pace to allow a career high in home runs, having already given up six across his six starts.
Corbin hasn’t been as good as he can be either, as he has pitched to a 4.91 ERA and a whopping eight home runs while also walking 11 and giving up 39 hits in 36.2 innings.
This is a mess. Nothing has gone right for the Diamondbacks this season. Their offense is okay, even with Paul Goldschmidt currently hitting .242. That will improve. So if their pitching lived up to their ability, the Diamondbacks would be just fine. They will live and die on the arms in their rotation, and right now those arms are killing their chances for this season. If the Diamondbacks are going to turn it around, it will have to start with Greinke, Miller and Corbin.