He went into the blue tent.

He was deemed questionable to return.

A short while later, he was back on the field.

Now, the San Francisco 49ers will be without De’Zhaun Stribling for an extended period of time. The latest word, from ESPN/NFL Network insider Ian Rapoport, is 4-6 weeks with the possibility of surgery if the sprain of the deltoid ligament in his left ankle doesn’t heal on its own.

The 33rd overall pick, who had generated so much buzz in the preseason, lasted less than 30 minutes in his NFL debut before he was carted into the tunnel — bitten by the organization’s injury bug.

Was it an unavoidable fluke that the first-year receiver’s left leg gave out while breaking on a route, causing him to tumble to the turf in the second quarter, shortly after being examined for an issue with the same ankle, or did he fall victim to a bigger problem?

Sometimes the evidence is too loud to ignore.

Kyle Shanahan awarded one of the game balls from the Week 1 win over the Rams to the training staff, for helping them adapt to the 17-hour time difference in Australia. When he takes the podium Wednesday before the Niners regroup for their first practice since getting home, he’s sure to face questions surrounding their role in losing their standout rookie receiver.

Maybe the ailment that sent Stribling into the blue tent in the first quarter was unrelated to the one that now could result in his placement on injured reserve. May we also interest you in some waterfront property on the Salton Sea?

Stribling hobbled off the field following a second-and-5 run late in the first quarter, attempting to put as little weight as possible on his left ankle. He went into the injury tent on the 49ers sideline and around the end of the period was ruled questionable to return.

By the first play of the second quarter, Stribling was back in the game. And at the 7:34 mark, he went down in a heap, grabbing at the same leg that 49ers trainers examined and deemed fit to return moments earlier. He played 21 snaps but didn’t catch a pass and now faces weeks if not months of rehab before he gets another chance at his first NFL reception.

If only it was the first time.

The last receiver the 49ers took with the top draft pick is already on injured reserve and expected to miss all of this season with an injury that he first suffered in Week 3 of last year.

Ricky Pearsall initially put off surgery and returned six weeks after injuring his PCL. But his knee never quite felt right and he eventually had the season-ending operation at the start of training camp.

Brock Purdy ultimately emerged all right after an offseason to recover, but should that time have come earlier, during the season, after initially suffering his turf toe injury in Week 1?

Purdy looked fantastic to open this season against the Rams, but he turned in his worst statistical year of his career while trying to tough through nine games last season.

Of course, the 49ers have been hit by so many injuries that some conspiracy-minded fans have been led to believe that an electrical substation adjacent to their practice facility is at the root of the problem. The theory hasn’t been definitely proven either way.

One area where there is real, anecdotal evidence is the training staff under Dustin Perry, who is in his 10th season and holds the title of vice president of player health and performance.

That’s according to the 49ers’ own players, whose grades added up to a C- rating in the category on the latest NFL Players Association report card, obtained by ESPN. The annual survey got responses from 1,759 players grading their own teams in 17 categories.

Overall, the 49ers ranked 14th. But their C- training staff came in 32nd — dead last.

The concerns were real enough that the 49ers looked into the substation problem (and found no evidence, but didn’t provide their research or cite who performed it), hired three new physical therapists and invested $9 million in new hot tubs, cold tubs and the like.

Their training room had also received a C- grade.

General manager John Lynch proudly announced the upgrades at the league meetings in the spring and players raved about the new amenities in training camp.

But apparently it didn’t address the source of the 49ers’ problem.