PHOENIX — The Diamondbacks went from one .300-hitting first baseman to another.

A year ago, it wouldn’t have been surprising to learn that in 2019, Arizona would have the NL’s doubles co-leader playing well on both sides of the ball, hitting .295 with a .949 OPS as of May 10. The surprise might’ve been that that player is Christian Walker, not Paul Goldschmidt.

Nearly 40 games into the season, several of Walker’s key offensive numbers are better than Goldschmidt’s, as is his WAR. Ironic, for a player who was stuck behind Goldschmidt in the Diamondbacks’ system and was expected to share first base with Jake Lamb when this season began.

When the injured Lamb returns from a quad injury, which could in the near future, manager Torey Lovullo will be adding a corner infielder when he has two productive ones already: Walker and Eduardo Escobar.

“Yeah, it’s going to be a huge challenge for me,” Lovullo said of balancing playing time when Lamb returns. “But what it means is we’re getting a really good player back in Jake Lamb. And now we have an extra bat, and extra guy, an All-Star that’s back in our lineup that’s going to help us win some baseball games.”

Lovullo has time to figure out what he’ll do, and nothing is set in stone. But the manager said Friday that as he looks at it now, Lamb could play some at third and Escobar could go to second base.

Walker earned the right to keep his spot.

“Definitely the back end of a lot of hard work,” Walker said when asked about his strong start. “Lot of reps, a lot of hours. But also, a sense of confidence that’s given to us from the staff. And it’s just in the atmosphere here: Everybody’s here for a reason. Everybody has a job, everybody has a role. Have confidence in yourself, trust yourself and go out and play.”

It’s probably not a coincidence that the increase in productivity has come in the same season as his increase in playing time (he’s already far exceeded his career high in plate appearances).

“I think there’s an element of just knowing that day-to-day, I’m going to be out there,” Walker said. “You always have tomorrow. Takes some of the pressure off of each individual at bat.

“It sucks that Lamb went down. I know me and him were really excited to tag team first base and I think that would’ve been a great situation. But moving forward, we’re looking forward to having him back in the lineup and I think the team still has room to grow.”

In 2017, Walker was in his first year with the D-backs organization after spending his whole career with Baltimore up to that point. That first season with the Reno Aces, Walker hit .309 with 32 home runs and 114 RBI.

But his production in 61 career major league games before this season amounted to a .170 batting average, six home runs, nine RBI and a .683 OPS in 99 plate appearances.

“I definitely had a lot of belief in myself, a lot of trust, a lot of confidence,” Walker said. “But it’s hard to stack yourself up against this competition until you get a certain amount of time against it. I still don’t think I’m there yet. I still have a lot of room to grow, a lot of reps to earn. And I’m just honored to be getting this opportunity.”