Starters' struggles a worrying trend for D-backs

PHOENIX -- Pegged by most -- us included -- as a pitching powerhouse before the season began, the Diamondbacks have been everything but.

But as inconsistent and ineffective as the rotation has been at times, the D-backs somehow sit fairly comfortably atop the NL West.  

Trevor Cahill's eight-run disaster in a 10-5 loss to the Giants on Saturday was the latest example of the disappointing start the D-backs have gotten from their rotation. Cahill's six-run fourth inning led to a second loss this week in which the D-backs were buried by a bad inning.

"That one happened in 24 pitches," manager Kirk Gibson said. "It happened quick. They scored six runs on 24 pitches."

Ian Kennedy gave up eight runs in an inning Thursday in St. Louis. Last Friday, Wade Miley gave up five in an inning. The blowup innings are a disturbing trend of late, even if they are partially the product of a pitcher's performance turning on a dime with no reliever ready to step in.

Cahill's meltdown took the D-backs out of Saturday's game before all but one hitter even had the chance to register a second at-bat. His season-worst effort was too much for the D-backs to overcome, though the D-backs have made a habit of winning despite a shaky starting rotation, currently holding a plus-25 run differential.

Now 62 games into the season, the D-backs have just one starter -- Patrick Corbin -- with an ERA below 4.00. Only Corbin, whose 1.98 ERA ranks third in the NL, has won more than four games.

Take a look at the numbers so far:

Cahill: 3-7, 4.02 ERA
Kennedy: 3-4, 5.72 ERA
Miley: 4-5, 4.92 ERA
Brandon McCarthy: 2-4, 5.00 ERA

McCarthy is now on the disabled list with shoulder inflammation, with young lefty Tyler Skaggs taking his place. But the four above are a combined 12-20 with a 4.78 ERA. Not exactly the deep rotation everyone expected.

"We'd like to have better performances, but it wasn't long ago they were dominating," Gibson said. "It's the ups and downs of a season. We'll have to reflect on try to get (Cahill) straightened out for his next start. Same thing with Ian."

True, the D-backs have seen a couple really strong turns through the rotation this year, but outside of Corbin's dominance, inconsistency has reigned.

The team essentially built in the image of the World Series champion Giants -- strong pitching, adequate offense -- has seen the script flipped, as the rotation and bullpen have swung between highs and lows and the offense has gotten an unexpected boost from the likes of Paul Goldschmidt, Didi Gregorius and Eric Chavez.

The old baseball cliché says that winning games comes down to pitching and defense, but the D-backs frequently have had only the latter. That's a testament to the offense, which remains the only one in baseball to avoid being shut out this season.

It was Gibson who said shortly before Opening Day that the D-backs "were not going to have a shot at all" if they didn't pitch well. So far, they are proving those words wrong, but it's hard not to wonder how long that can last.

"Corbin's been really good, and we've had our ups and downs, but I think we'll kind of just keep plugging away, take it one start at a time," Cahill said. "It should work itself out."