PHOENIX — Jon Duplantier will make his first ever Major League start tonight. And it suddenly holds a lot more meaning for the Arizona Diamondbacks.

The 24-year-old righty has long been considered one of Arizona’s top prospects, so his first start was already eagerly anticipated by a fanbase that has seen the rotation depleted lately. Patrick Corbin left in the offseason, Robbie Ray can’t seem to get past the fifth inning anymore and Zack Godley’s struggles have landed him in the bullpen.

On the other hand, Luke Weaver has emerged as a solid second option behind Zack Greinke. But that will have to be put on hold for the foreseeable future now as well, as Weaver recovers from a mild flexor pronator strain and a mild UCL sprain.

“I don’t know how long it’s going to be,” Torey Lovullo admitted. “You guys want to know ‘when does he start throwing again?’ I don’t know how long that’s going to be.

“This will involve no throwing, and we’ve got to let this heal. We’re going to obviously be in constant contact with Luke and, as we start to see this heal, we’ll start to get you guys the next necessary pieces of information.”

In other words, it could be awhile. On the bright side, Lovullo added that no procedure would be necessary. And that’s not always the case when a pitcher starts feeling discomfort in his forearm.

Still, Weaver has clearly been one of the D-backs’ most valuable players through the first third of the season. He’s been one of the few consistently reliable pitchers on the staff, second only to Greinke. And his 3.30 ERA and 1.11 WHIP have exceeded expectations up to this point. This is a big void to fill.

Which is where Duplantier comes in.

The opportunity seems to be there for the rookie to stick in the rotation for awhile, if he’s up to it.

In four career relief appearances, he’s sporting a 2.25 ERA with a win and a save on his resume already. But this is different.

He’s stretched out and ready to go as a starter now, which is what the organization ultimately envisioned for him all along. Managing his pitch count will be important early on though.

“You usually build one inning and add on 15 pitches per outing,” Lovullo explained. “That’s a good starting point right there. We want to get as much out of him as we can.

“We want to get as much mileage out of him to preserve a bullpen that was a little taxed over the past four days. Given that, we’ll follow basically the same guidelines as we always do, where we add on an inning and 15 pitches.”

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