PHOENIX -- Third baseman Josh Rojas was walking through the cafeteria adjacent to the home clubhouse before Monday night’s game vs. the Pirates when he spotted starter Zac Gallen sitting with pitching strategist Dan Haren.

The pair were going over the Pirates hitters in detail and Rojas was mesmerized.

"The biggest thing is not only does he have nasty stuff, but you know so much goes into it before the game," Rojas said. "[They were] going over every hitter -- where their cold zones are, what to throw early in the count, what to throw with two strikes."

The prep work is all part of the meticulousness and dedication with which Gallen approaches his work and it has certainly paid dividends for him.

Monday was another example of it as he tossed seven scoreless innings in Arizona's 3-0 win at Chase Field.

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"A lot goes into starts and he's doing so much research. And once he gets out there, there were hitters that came up that I had heard them go over, and I had a feeling I knew what was coming,” Rojas said. “So it was pretty cool to watch."

Haren, who spent 13 seasons in the big leagues, including parts of three seasons with the D-backs, is someone Gallen respects and the two have built a close working relationship.

"Both Zac and Dan have very like minds and love information," D-backs catcher Carson Kelly said. "So that's why I think they really collaborate well together and come up with the best possible game plan."

It helped on this night that Gallen was able to draw from his four-pitch mix with his slider being the best it has been all year.

It's a feel pitch for him and one that he has been really working hard on all season long.

Before the All-Star break Gallen started to get a better feel for it, then watched some video of it afterwards. Finally, while playing catch in Atlanta during the D-backs’ recent road trip, it clicked for him and he felt better with it in his last start against the Guardians and then took another step forward with it Monday.

"It's just something that has honestly been like a six-week process," Gallen said. "It was something I've been diving into all year. In Cleveland I was like, ‘OK, I think I'm really close.’ And then just mechanically I felt pretty good about it and then you know, it's to the point where it's like, ‘OK I'm getting that very familiar feel of how it will come off my hand when I thought it was a really successful pitch. So, I'm just going to try and harness that and keep it going as long as I can.’"

As he listened to Haren and Gallen break down the Pirates hitters in the cafeteria, Rojas couldn't help but interrupt with a request that he thought might help him at the plate.

"I was kind of joking like, 'Hey, man, do me, I want to know what I might see up there,'" Rojas said.