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Is this Arizona Diamondbacks’ rotation the best ever?

It’s an eye-opening claim. But by one measure, it’s unmatched in over 70 years

MLB: Houston Astros at Arizona Diamondbacks Mark J. Rebilas-USA TODAY Sports

When Zack Godley starts tomorrow night against the Los Angeles Dodgers, he’ll be making his 20th start for the Diamondbacks. That will push our 2017 starting pitching into extremely rarefied territory. Here are the ERA+ figures for the five main members of our rotation to date:

  1. Robbie Ray - 154
  2. Zack Greinke - 150
  3. Zack Godley - 149
  4. Taijuan Walker - 132
  5. Patrick Corbin - 120

So far, they’ve been responsible for 88% of games, with all other pitchers combined making only sixteen starts. There’s still a month left in the season, so it’s possible for one of the above players to fall off [though the way Corbin has been pitching of late, I would be inclined to take the over on his ERA+] But here’s the startling thing.

No team in the integrated era of baseball has had five pitchers make 20 starts, all with an ERA+ of 120 or better.

The last to do it, were the 1942 Detroit Tigers, led by Hall of Famer Hal Newhouser (23 starts, 162 ERA+). He was backed by Tommy Bridges (22, 144), Hal White (25, 136) and Al Benton (30, 136). But they only just qualified too, Virgil Trucks filling out the fifth spot in their rotation with exactly 20 starts and an ERA+ of 145. Before those Tigers, you need to go back, deep into the dead-ball period of baseball history, and the 1907 Cubs, where another Hall of Famer, Mordecai ‘Three-Finger’ Brown anchored their staff.

Now, you could argue this is a result of the death of the 4-man rotation. But if you adjust the parameter to 25 starts (allowing for the shift from a 5-man rotation), while keeping the ERA+ cutoff at 120, you don’t get many more hits from the live-ball era. Indeed, the only team with four such starters since the Great War, are the Atlanta Braves of 1997 and 2002 (Tom Glavine + Greg Maddux), and the 2001 Oakland Athletics (Tim Hudson, Mark Mulder and Barry Zito). No-one has ever had five: if Godley pitches as he has the rest of the way, and Corbin’s ERA+ doesn’t drop, the D-backs could be the first ever. In terms of “high floors”, this rotation is certainly an excellent one.

Of course, there are other metrics you can use, which don’t portray the 2017 D-backs in such a glowing light. By fWAR, the rotation has accumulated 15.6 wins, which is not bad, being the best in the National League. But even in team history, that would put them on pace for 19.3 fWAR, good enough only for fifth in the Arizona rankings. The 2001-03 rosters, as well as surprisingly the 2008 D-backs, all put up more. The main reason is, those teams had better 1-2 punches at the front - Schilling/Johnson, Schilling/Webb or Webb/Haren - which countered their weaknesses at the back of the rotation.

Nothing illustrates this better than the 2001 roster. Curt Schilling and Randy Johnson combined for 69 starts and 16.9 fWAR that season. [The fact they threw almost 500 innings between them didn’t hurt!] Everyone else who started for Arizona that year, combined for 93 games and only 2.7 bWAR. The team this season doesn’t have anything like that kind of split. Our two best, Greinke and Godley, have been worth 7.2 fWAR to date; everyone else 8.4. It’s a much more balanced set of starting pitchers, though this could be a double-edged sword: 2001 showed us how far you can go, with a true pair of aces. In the playoffs, your 1-2 are more important than your 4-5.

But it’s a thoroughly impressive turnaround. With more than a month still left to play, this year’s starting pitching has all but DOUBLED the fWAR from last season’s rotation, which managed only 7.9 fWAR. [For comparison, our offense is at 14.7 fWAR, just coming up on the 2016 figure of 16.0] There’s no doubt that, when the story of the 2017 Diamondbacks is written, it will be the story of their starting pitching.