PHOENIX -- The news wasn't unexpected for the Diamondbacks, but neither was it welcome.

The Astros' agreement with first baseman Christian Walker to a three-year, $60 million contract on Friday leaves a big hole in the Diamondbacks' lineup and clubhouse that they must now look to fill.

Since taking over at first base in 2019 for Paul Goldschmidt, Walker has been a mainstay. From '19-24, Walker slashed .253/.332/.464, while winning three straight Gold Glove Awards.

The Gold Gloves only tell part of the story on defense, as Walker is the best-fielding first baseman in Statcast history.

In addition, Walker became a leader in the clubhouse with players sitting around his locker postgame discussing the just-finished game, and he set the tone with his hard-nosed style of play.

At their joint end-of-season press conference, both general manager Mike Hazen and manager Torey Lovullo heaped praise on Walker, who was claimed off waivers by Hazen in the spring of 2017, his first year as GM.

"We have a long history [with] Christian Walker, way back in the day when he was an up-down guy in Triple-A for us," Hazen said. "And the amount of pride that I think, and I'll speak for Torey, that we have in what he has accomplished and made himself into as a player is something that I'm extremely proud of from an organization standpoint. He's become the best defensive first baseman in baseball by a long shot. He's earned all that. Obviously, as a power hitter, that speaks for itself, and he's done that year over year over year. He deserves everything that's coming his way."

What is coming the Diamondbacks' way is a compensation pick between the first round and the Competitive Balance Round A in next year's MLB Draft. That's because Arizona made Walker a qualifying offer, which he rejected.

Where the Diamondbacks go from here to fill Walker's spot remains to be seen.

While the fan base might long for a reunion with Goldschmidt, that doesn't seem to be likely at this point. There are free agents out there like Carlos Santana and Josh Bell who could fit, or Arizona could work out a trade.

The Diamondbacks do have options internally, including former first-round pick Pavin Smith, who has not gotten an extended look at the position since being selected seventh overall in 2017.

"He hits the ball hard," Hazen said of Smith. "He has a great approach. He started lifting the ball a little bit more. He hit a lot of home runs. You extrapolate that out over a full season, and you got a pretty good season. He needs to do more work defensively at first base. And he has the capability to do that, he works hard, he'll figure that out. We haven't given him enough runway or opportunity to really see what he can do."

Whether the Diamondbacks give Smith that runway or sign someone to either play first base full time or platoon with Smith remains to be seen.