PHOENIX — If there’s been one constant with Robbie Ray this season, it’s that he won’t pitch deep into a baseball game.

Entering Sunday’s game against San Francisco, he had made it through six full innings just twice in nine starts.

The outing against the Giants would have been a good time to reverse that trend considering Zack Godley lasted just 3.1 innings the night before.

Ray couldn’t provide that. The lefty made it through just four innings — his shortest start of the season — and the D-backs’ bullpen faltered late in a 3-2 loss in 10 innings to San Francisco.

Arizona (25-22) finished its 10-game homestand 4-6.

“Obviously, you want to go deeper than four innings every time,” Ray said after the game.

Ray’s start was destined to be short from the beginning, a dangerous spot in which to put a troubled D-backs bullpen and an offense that struggled to solve Drew Pomeranz and the Giants bullpen.

An almost 30-pitch first inning set the table for the rest of his start. Through three innings, Ray was up to 73 pitches and he allowed a pair of runs in the third inning that put the D-backs behind.

Ray probably would have come out for the fifth inning but with 87 pitches and the D-backs threatening in the fourth inning, he was lifted for a pinch hitter.

“Robbie didn’t have his best stuff,” D-backs manager Torey Lovullo said after the game. “I thought he was having trouble landing his secondary stuff. At times, he was a little erratic with his fastball command.”

Arizona ended up scoring twice in the inning but it forced the D-backs bullpen, which had allowed four runs the night before, to be called upon for an extended period once again.

The D-backs ended up getting five consecutive scoreless innings from Jimmie Sherfy, Andrew Chafin, Yoan Lopez and Greg Holland, but a 10th-inning home run from Pablo Sandoval off Yoshihisa Hirano proved to be the difference.

Ray’s lack of efficiency is nothing new, but it’s concerning considering the D-backs bullpen has been getting stretched thin recently.

His spot in the rotation directly follows the one currently occupied by Godley and the future and reliability of whoever ends up in that position is spotty.

Plus, the D-backs rely on Ray more than any other starter not named Zack Greinke because of his past success.

Just two seasons ago, Ray had a career-high 16 quality starts. This season, he has just one quality start in 10 appearances.

“It’s definitely not what you want from some starting pitchers,” Lovullo said of his starters’ short outings. “We want our guys to go deeper into games, that’s for sure.”

Thankfully, there’s a path to a more effective and efficient Ray.

Keeping the pitch count low is the obvious solution. For Ray, that means connecting on more of his secondary pitches and limiting walks.

Ray tied a season high with four walks against the Giants.

Even so, Ray’s ERA sits at 3.25 despite his efficiency problems.

“I’m still going out and trying to fire zeroes and I feel like I’ve done a pretty decent job of that,” Ray said. “Pitch count just got elevated early because of those tough at-bats.”

There’s no rest for the D-backs, who open a three-game series Monday on the road against the San Diego Padres.

“Things lined up the way we wanted them to, but we just came up a little short,” Lovullo said.

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