PHOENIX -- Some time in the next week the D-backs will likely go from 13 pitchers to 12 in order to add a bat to the bench.

A good bet would be after Monday’s off-day, by which point their bullpen should be fully rested. It was after an extra-inning game in Dodger Stadium -- and some short outings by their starters in that opening series -- that forced them to add an extra arm in the bullpen.

That turned out to be right-hander Jon Duplantier, the organization’s top pitching prospect, according to MLB Pipeline.

Duplantier tossed three shutout innings in relief in his lone appearance so far. While it would appear that sending Duplantier down when they add a bat would be the most likely scenario -- that way he could get into the Triple-A Reno rotation and continue his development -- it’s not a sure thing.

“The development of [Duplantier] is extremely important to us,” D-backs general manager Mike Hazen said. “It always has been. He has hit a level of his career where he made it up to the big leagues, and pitching in a role to help us win games can supersede the development. That’s what happened in this case. We still view him as a starting pitcher, so we want to make sure that he has the opportunity to start, but there’s no blueprint for this necessarily. If he’s going to continuously get outs up here and he’s the right guy, there’s no guarantee that we’re going to go in any one particular direction.”

Homecoming

Merrill Kelly already made it through the pressure of his big league debut when he beat the Padres last week in San Diego, but now he faces a different kind of anxiety -- pitching in a regular season game at home for the first time.

Kelly went to high school and college in the Phoenix area so pitching for the D-backs in Chase Field is a dream come true.

“Special for sure,” Kelly said. “Anytime that it’s home and the people that have been following me for a long time, but haven’t necessarily gotten to see me throw.”

Kelly threw in Chase Field during the team’s final exhibition game, which is a benefit.

“I would say, if anything, just some familiarity,” he said. “When I get on the mound, the backdrop I will have already seen, the tunnel to the plate, the whole look of it. I just won’t be surprised.”

Kelly expects to have around 35 friends and family on hand to watch him Sunday.

Injury updates

Taijuan Walker, who is working his way back from Tommy John surgery, threw a 40-pitch bullpen Saturday and will throw another next Friday.

Meanwhile reliever T.J. McFarland (shoulder inflammation) threw 20 pitches facing hitters. McFarland is still probably a couple of weeks away from returning.