What will Diamondbacks 1B Josh Bell’s role be when Christian Walker returns?

PHOENIX — As Arizona Diamondbacks first baseman Christian Walker inches closer to returning from the injured list, the club has a decision to make with trade deadline addition Josh Bell’s role down the stretch of the season.

Walker (oblique strain) has been hitting off live pitching and facing the Trajekt machine — which mimics a specific pitcher’s windup. Manager Torey Lovullo said a return by Sunday when rosters expand to 28 is improbable but not out of the question. A return next week against the San Francisco Giants appears more likely.

Bell has played nearly every day in Walker’s place after coming over from the Miami Marlins, and Lovullo does not intend to revert the switch-hitter to a solely pinch hitting role when Walker reenters the batting order.

“He’ll play against every left-handed pitcher, that’s for sure, and then select right-handed pitchers,” Lovullo said. “He’s definitely going to play. He’s not going to ride the bench. We’re anxious to get Christian back, but he’s going to be on a little return-to-play progression. Christian will not get here and play 28 or 30 straight games, he’s going to need some time down.”

Bell slashed .261/.340/.457 with four home runs in his first 24 games with Arizona entering Friday’s matchup against the Los Angeles Dodgers. He has a .669 OPS against lefties and .862 versus righties, although his career splits are pretty even.

The 32-year-old veteran hit four homers in his first six games after the trade. The D-backs sent cash considerations to Miami for Bell, whom the Marlins placed on waivers.

“I’ve asked him to play a lot,” Lovullo said. “He’s doing it on both sides of the ball. He’s collecting the baseball defensively. He’s got some huge hits for us offensively. And it’s been great to watch him go to work.”

Having Bell play against every lefty brings up questions about how the Diamondbacks will manage their outfield, as Bell would likely have to be the designated hitter with the Gold Glover Walker at first base.

Arizona would have to pick three of Lourdes Gurriel Jr., Randal Grichuk, Jake McCarthy and Corbin Carroll on a given day against a southpaw starter — essentially choosing between the lefty bats McCarthy and Carroll. McCarthy has the exact same OPS against lefties and righties at .806, although his numbers left-on-left have dropped significantly in the past couple weeks. Carroll is better against righties but has turned on the power against both right-handers and southpaws this month.

Christian Walker, Ketel Marte injury updates

Ketel Marte (ankle sprain), like Walker, has been hitting live pitching and the Trajekt machine. He has been batting from both sides of the plate and will start to get more work in with spikes.

“All the intensity is starting to ramp up and that’s by design, because we want these players to really let their bodies go more into a natural space, natural reaction and then we can grade it out from there,” Lovullo said. “So far, so good. Everybody was doing fine. There’s also ground balls, there’s flips, soft toss, a lot of those things we’re looking for.”

Lovullo said he believes Marte is going through more trials than he had after initially injuring his ankle on Aug. 10, after which he exited two games early before hitting the IL.

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