The Arizona Diamondbacks made their first Postseason appearance since 2011 last season on the heels of a historic pitching performance. In terms of ERA+, it was the 7th best performance since 1947. Repeating that level of dominance will be difficult and, quite frankly, not likely. The humidor should greatly benefit most members of the pitching staff by not only reducing the amount of home runs hit at Chase Field, but by also improving the grip and tackiness of the game ball. Through increased usage of superior secondary pitches combined with the installation of the humidor, the pitching staff could possibly come close to that 2017 performance again.

The depth among the starting pitching staff is remarkably thin compared to last season. On April 23rd against the Los Angeles Dodgers, Shelby Miller was forced to exit the game after completing only four innings, and it was shortly announced that he would need Tommy John Surgery. In need of a replacement for the rest of the season, Zack Godley was called up from AAA Reno. His string of strong performances would eventually lead to him becoming a mainstay on the starting rotation, but not before he was shuttled back to Reno a few more times. The Diamondbacks gave Braden Shipley the opportunity to fill Miller’s spot in the rotation, but Godley ultimately won that competition between the pair thanks in large part to his dominant curveball (we will touch on that shortly).

That was not the conclusion to the strong performance the Diamondbacks received from their replacements. When Taijuan Walker missed a handful of starts due to blisters on the fingers of his throwing hand, Randall Delgado stepped up to make five appearances as a starter and was more than respectable while filling in. Through 25 innings as a starter, he maintained a 2.52 ERA, 2.88 FIP and 3.05 xFIP. Now that is a remarkably small sample size for a starting pitcher, but the point of this is not to project any type of performance from him going forward. Those were real figures that he accumulated in an emergency when two of our starters were on the disabled list. Not bad for a guy who seemingly had no future as a starting pitcher after five prior seasons in Arizona.

Fast forward to the present day and you will find that Shelby Miller, unsurprisingly, is still on the shelf until at least the middle of the season. Zack Godley will likely be a member of the starting five come Opening Day barring injury during Spring Training. Unfortuantely, the extended outings last season perhaps took their toll on Delgado for he did not make another appearance after July 15th with soreness in his throwing elbow. Expecting him to repeat or even come close to what he provided last season would probably be a mistake. Out of all of the pitchers who made starts for the Diamondbacks last season who were not named a member of the starting rotation on Opening Day, Godley and Delgado accounted for 30 “replacement” starts out of a total of 38 that were made.

It would be foolish to think that injury could not strike again this season. Our two best replacements from last season will now be expected to contribute on a regular basis (Godley) or has questions surrounding his health (Delgado). Anthony Banda accounted for another 4 of those “replacement” starts, but he has since been traded to Tampa Bay thus removed from the picture as well. As the roster is currently constructed, the Diamondbacks can hardly afford an extended absence from any member of their starting five let alone two at the same time. Certainly, Braden Shipley could have an epiphany similar to Godley’s last season and assert his own dominance, but he has so far failed to produce above AAA. Other possible options, in no particular order or reason, include: Taylor Clarke, Matt Koch, T.J. McFarland (please no), Kris Medlen, or Archie Bradley (highly unlikely).

So where do we go now?

This post was/is meant to serve as to how I think Diamondbacks’ starting pitchers could be as formidable as they were last season, so allow me to correct course. In my opinion, what has not been discussed enough is how the Diamondbacks were able to go from one of the worst pitching staffs in 2016 to one of the best in 2017. Plenty have offered theories ranging from a refined philosophy on pitch framing to the benefits of advanced scouting provided by Dan Haren. The impact of pitch framing is still debated by many, and Haren’s contributions cannot be readily measured or observed by any of us.

However, what has been quantified is the Diamondbacks’ increased usage and remarkable success of their breaking pitches in 2017. I am specifically referring to the curveballs of Godley and Robbie Ray. I am specifically referring to the sliders of Walker and Patrick Corbin. Both pitches require adequate feel and grip to throw effectively, something the humidor should hopefully assist with greatly.

We start with Godley who is mainly a four pitch pitcher relying on a changeup, cutter, sinker, and curveball. He has thrown a total of 9 four seam fastballs in his three Major League seasons and completely abandoned the pitch last season, so we will exclude that pitch. You can readily see that he has tripled the usage of his curveball since he entered the league in 2015 throwing it over 35% of the time in 2017. Can you guess which pitch has been his best over his career? In terms of wRC+, that would again be his curveball with a whopping 28 wRC+. Put more simply, this means that opposing batters fair 72% worse than league average against his curveball in terms of creating runs. His sinker and cutter have been much more inconsistent than his curve with the former producing the worst results it has for him during his career in 2017 while the opposite is true for the latter. The point here is that his curve has consistently been his best pitch over his career, and his increased usage of it in 2017 took his game to another level.

Let us move on...

For Robbie Ray, I have skewed the filters to help drive home the point I am trying to make. Missing from the chart above is his fourseam fastball which as we all know has been his most widely used pitch since arriving. By removing that noise from the data, you can more clearly see that he too increased the usage of his curveball last season at the expense of his sinker and changeup. Can you guess out of those three pitches which two were the worst and which was one of his best? Robbie Ray is a bit more interesting because he arguably had to develop his curveball to survive as a starting pitcher. When he was first acquired from the Detroit Tigers, he had difficulty putting hitters away. This often led to elevated pitch counts which usually saw him exiting the game somewhere close to the 5th inning. By nearly eliminating his two worst pitches and utilizing his newfound curveball, he was in the Cy Young conversation for most of the season before a comebacker sidelined him for a few starts (again depth is a necessity). For his career, he has a 144 wRC+ against his sinker, 177 wRC+ against his changeup, and a 37 wRC+ against his curveball. That is an adjustment which could lead to enormous success.

The story for Patrick Corbin is a little bit different than it was for Godley and Ray. Corbin has always had a slider, and it has been his best pitch by far over his career. His sinker, fourseam, and changeup have all been hit particularly hard throughout his time in the big leagues, but hitters struggle to make meaningful contact against his slider as it has the highest percentage of whiffs and lowest isolated power outcome in his repertoire. Whether that pitch put added stress on his elbow and led to Tommy John Surgery is not going to be discussed here. When his slider is working and falling near the back foot of a right handed hitter, it is one of my favorite pitches to watch. With all that being said, it was in his best interest to increase the usage of his slider which is exactly what he did in 2017.

Taijuan Walker revealed last Spring Training that he was working on his slider in order to use it with more effectiveness during the regular season, and it would appear he accomplished that goal. That increased usage came at the expense of his cutter which he eliminated completely in 2017, and he reduced the amount of splitters he threw too. His splitter and cutter were fairly similar in regards to effectiveness (ineffectiveness?) in that the former carried a 116 wRC+ over his career while the latter holds a 115 wRC+. The slider you ask? 78 wRC+. Again, I removed his fourseam usage from the chart above for clarity.

Okay, so why is any of this relevant?

The two pitches discussed above for the four starting pitchers require adequate grip to throw with any effectiveness. Without any feel for the slider or curveball, chances are that any one of those named above are going to have a difficult outing. The increased usage of the pitches highlighted above come at the expense of lesser secondary offerings from them. Equate it replacing a Gregor Blanco with a J.D. Martinez in the lineup. We might not know who to thank for that change in strategy, but at least we know it worked.

With roughly half of their starts coming at Chase Field, now complete with the install of the humidor, dare I assert that they could potentially be as effective as they were last season? The organizations’ hope is that the humidor will increase our pitching staffs’ grip on the baseball. That is what they have stated ever since it was announced last season. If that hope comes to fruition, Ray, Godley, Walker, and Corbin could have secondary pitches that are even more successful this season than they were last. That all comes before we even begin to consider the potential for a reduced amount of home runs surrendered at Chase Field.

Additionally, there should be better defenders behind our pitching staff in the field this season. If Nick Ahmed is not limited because of his prior hip injury, he can be one of the best defensive shortstops in the game. We also no longer have to worry about the defensive liability of J.D. Martinez, and Yasmany Tomas’ playing will likely be limited too. Jarrod Dyson and Steven Souza Jr. have a superior ability to turn balls in play into outs.

Repeating the success that last season’s pitching staff had will be no easy task, but there is a road map. It will require a tremendous amount of luck in regards to health if depth additions are not made. If the starting five is able to remain on the field and throw those breaking pitches with effectiveness, we could be witness to an encore.