Everything about the moment seemed surreal.

San Francisco 49ers quarterback Brock Purdy was pounding a fist across his chest on Sunday night and screaming “WHAT’S UP!?” to seemingly nobody and everybody. The team’s left tackle, Trent Williams, walked up behind him and broke into a wide smile while clapping into Purdy’s energy. The stands around him were chanting “Purr-dee! Purr-dee! Purr-dee!” like this was the anticipated arrival of a first-round franchise centerpiece rather than the last pick in the 2022 NFL draft.

In the middle of it all, the Tampa Bay Buccaneers were getting thoroughly trounced on the way to a 35-7 loss to the 49ers and had to be wondering if maybe Purdy had a point with his boisterous rhetorical question.

What. On Earth. Was up?

This felt like a stunner. Not because a struggling Buccaneers offense got pounded by the best defense in the NFL, but because Purdy was only expected to step into the starting lineup for San Francisco and not screw things up. At absolute most, he needed to be a Xerox of a game-managing Jimmy Garoppolo. A few hours later, he looked like he might have a chance to be more, which should be scary for NFC elites like the Philadelphia Eagles and Dallas Cowboys. The last thing they expected was for Garoppolo to go down with a long-term injury and to see the 49ers' offense actually look better.

Yet, for at least one game against a solid Tampa Bay defense, that’s what happened. Purdy, the four-year starter at Iowa State who was just good enough to be drafted after 261 other players in April — earning the back-handed compliment of being “Mr. Irrelevant” as the last player chosen — was so much more in his first start in San Francisco. Aside from an efficient stat line (16 of 21 for 185 passing yards, with two passing scores and one rushing touchdown), it was how Purdy played that struck a chord.

He was decisive, accurate and made off-schedule passes. He made completions with defenders in his face. He bounced back after being crushed in the pocket while delivering a flawless 27-yard touchdown to running back Christian McCaffrey — which Purdy squeezed between McCaffrey and the sideline, where no defender could get it. His rushing touchdown? Deft. His throws on the run? Well, one cross-body completion to wideout Deebo Samuel was an eyebrow-raising dart between Buccaneers defenders.

If you saw Purdy at Iowa State, this was his forté. He was a slightly undersized but exciting player who had a penchant for making things happen off script. Of course, he also made some memorable mistakes, too, which is what you get with a player who falls all the way to the last pick in the draft despite being a successful four-year starter in a major conference. The highs are very high and memorable, especially on days like Sunday when Purdy is playing without turnovers or big mistakes.

As 49ers head coach Kyle Shanahan told reporters, “He reacts and runs around and makes some plays. That’s how he was in college. And that’s how he’s been so far in the league. When you do that, it’s how many good plays can you make without making the bad ones. He’s done that really well so far.”

While Shanahan said he was impressed, we really should have known how he felt about Purdy in August, when the team cut fellow backup QB Nate Sudfeld after giving him a fully guaranteed $2 million for the 2022 season. When that happened, the move was largely focused through the lens of Garoppolo restructuring his contract and returning to the team to back up Trey Lance. But those closest to the 49ers knew it was because general manager John Lynch and Shanahan were impressed with what Purdy had shown in training camp and the preseason. Yes, cutting Sudfeld had some cost savings, since the 49ers knew another team would pick him up and pay at least $1 million in salary that would offset part of what San Francisco owed him. But part of it was because Shanahan was impressed with Purdy’s skills, cocky competitiveness and willingness to push whoever he was playing with on the scout team.

All of that was on display Sunday against the Buccaneers. It’s how Purdy became the first Mr. Irrelevant to throw a touchdown pass in the NFL. It’s how he became the only rookie to get a win against Tom Brady in his first career start. And it’s how, with eight minutes left and the 49ers leading Tampa Bay handily, Shanahan pulled Purdy out of the game to protect him.

A move that, along with Purdy’s exciting and emotional day, had some people already losing their minds. Some drew comparisons to Tom Brady coming off the bench in 2001 for the New England Patriots as a sixth-round draft pick and never giving the job back to Drew Bledsoe. Or suggesting flippantly that maybe Purdy could steal the 49ers' starting job from Garoppolo and Lance. They were overreactions that fit perfectly into a surreal day.

For now, the fact remains. Purdy is San Francisco’s quarterback during this hopeful Super Bowl run. And he asked the pertinent question Sunday: What’s up?

Nobody knows. But he’s taking the franchise for a ride. For better, worse … or maybe a lot further than anyone expected a just week ago.