In a bit we should learn the extent of Brandon Belt's knee injury, but this much is clear. He is going on the 10-day disabled list, one of a flurry of roster moves the team accomplished Wednesday and Thursday ahead of a four-game series at AT&T Park against the Brewers - crucial for the front office as it goes about its buy-sell-hold Hamleting.

Here is the upshot: Evan Longoria was activated from the DL and will return to the lineup for the first time since his hand was broken in Miami in mid-June. Chris Stratton was promoted and Kelby Tomlinson optioned.

Tomlinson is the 2018 yo-yo. He has a punch card. One more trip back and he gets to be Speaker of the Assembly.

The other two moves are self-canceling. The Giants actually optioned reliever Ty Blach to Triple-A after Wednesday's game, then recalled him to replace Belt.

Stratton will boost a bullpen that has been used a lot and was down a man as soon as Derek Holland moved into the rotation. The Giants are back to 13 pitchers and a five-man bench.

Longoria went 3-for-14 during his four-game rehab stint for the River Cats. Fear not, Sacramento fans! Now you get Joe Panik, who officially began his rehab several days ahead of schedule.

Belt's injury answered one of the questions swirling around Longoria's pending return: Would he become the everyday third baseman again, or platoon with Pablo Sandoval?

Now, Sandoval will be the regular first baseman. Buster Posey has not been playing first base on his days off because of his lingering hip issue, but he could.

Longoria will face a lefty in his first game back, Wade Miley. The Brewers then throw three righties.

Core struggle: The Giants clearly need to investigate bats if they are serious about adding before the trade deadline, but a trade will not do them any good unless somebody - anybody - else starts hitting.

Belt was in a 1-for-33 when he got the infield single that injured him in Seattle on Wednesday. Brandon Crawford, who had a bloop RBI double Wednesday, has seen his average fall from a high of .338 to .284. Buster Posey has three extra-base hits in his past 22 games (all doubles) while Andrew McCutchen has had two extra-base hits in a 14-for-66 July.

When you hear some fans scream "sell!" these are the kinds of numbers that scare them because these players are going to be around for a long time. These are also the guys who have a history of hitting, even recently, who will have to do so again for the Giants to prosper with our without an offensive upgrade.

"It does come down to, to be honest, your core guys that you count on," manager Brace Bochy said. "I know we've got less than 60 games now, but we'll get this thing somewhat consistent."

It sounds like a pipe dream. Then again, the thought of the Pirates winning 11 in a row two weeks ago was a hallucination.

Holland return? After allowing two runs in six innings Wednesday, one earned, Holland sang the praises of the organization for its ability to have so many good replacements for players to get injured.

So he was asked if he likes the organization enough to return next year?

"We'll see," he said. "I love it here. There's no doubt, and I think my two uncles do, too."

Holland has talked about a couple of uncles who live in Arizona and New Mexico who are big-time Giants fans and wanted him to sign here, the ones who, ahem, secretly rooted for the Giants against Texas in the 2010 World Series when the lefty was a Ranger.

Holland is a free agent after the season. He's been great for the rotation, great in the bullpen and great in the clubhouse, the kind of guy the Giants probably should think twice before discarding over a few dollars.

The balk: Holland was not happy with first-base umpire Paul Nauert after a balk call Wednesday. Holland did not think he balked, but that's not what bugged him most.

"Umpires are going to make their calls and I'm not going to sit here and make any discussions about him," Holland said. "I can see where I stepped. It's his call, not mine. I did try to ask what I did. The one thing that did upset me is I did ask him fairly nicely. I wasn't giving attitude yet. He stared to raise his voice.

"To me that bothers me a little bit. I just wanted to see what I was doing. I'm not going to stress about that that. It's more upsetting we lost the game."

Henry Schulman is a San Francisco Chronicle staff writer. Email: hschulman@sfchronicle.com Twitter: @hankschulman