One tough loss not proof Warriors are pastry patsies, main course yet to come

They will win this series, almost surely, since no NBA team has ever won after being down 3-0 in a playoff series, but stiffer physical tests lie ahead, like in Game 5 on Wednesday, and then in the next round against Minnesota or Memphis.

There were many reasons for the Warriors’ 126-121 loss Sunday, but let’s go to Steve Kerr for a quickie analysis:

“They were the most physical team,” the Warriors’ coach said. “We didn’t deserve to win.”

It wasn’t a dramatic butt-kicking. The Warriors actually outrebounded the Nuggets 36-33 and limited the Nugs to a mere five offensive rebounds. But Kerr felt his crew got out-toughed. That’s death in the playoffs.

Don’t believe Kerr?

“They played with more force, at both ends of the floor,” Warriors forward Draymond Green said.

The Cupcake Question is nothing new to the Warriors, or to teams on this left edge of America. The Showtime Lakers, currently featured in a highly fictionalized TV series, always fought that rep. Magic and Kareem and the L.A. fellas always seemed to face tougher, nastier foes. See: Bad Boys Pistons, Clothes-lining Celtics.

Funny thing, though. Those tea-sipping Lakers won five championships and it would have been six if not for a Magic Johnson injury.

The Warriors, in their five-season run to the Finals, always heard whispers, and shouts, that they were tiptoeing through the tulips and would soon get crushed. It never happened, but it’s a theme that some critics, experts and assorted haters love to pound.

Who can forget the tombstone cookies LeBron James shared in the Warriors’ honor after his Cavs came back from down 3-1 to win the title in 2016? Or the cupcakes that became the NBA symbol of softness when Kendrick Perkins trolled Kevin Durant for jumping to the Warriors. Who can forget how old-school know-it-alls scoffed at Stephen Curry’s MVP trophies, saying he would have been torn limb-from-limb in the old days of “real” basketball.

A lot of that talk is silly bluster and blow back against a team having too much fun for some observers. But the playoffs are a grittier brand of ball, and the Warriors do seem to get smaller and lighter and more finesse-y by the day.

That Cupcake Question is even more legit now that the Warriors are occasionally trotting out a new three-guard lineup, with the lightly nourished Jordan Poole joining Curry and Klay Thompson.

On Sunday, Poole had his first subpar game in what seems like two months, just 11 points. He did have nine assists and three steals, so not a complete slug, but Poole didn’t swing the ball enough when he got blitzed, reverting to old habits.

“They were more physical with (Poole) tonight, for sure,” Kerr said. Aaron “Gordon got into him. That should be expected at this point. Jordan has made a name for himself around the league, and he’s played so well, so teams are going to start throwing a lot of stuff at him, including physicality and trying to get under his skin a little bit. So good experience for Jordan, he’s got to go through it to feel it, and then he’ll respond in Game 5.”

So if you’re looking for a silver lining, there you go. Some Warriors went to school Sunday. Had they won, the lessons might not have hit home, and this team really needs to storm into the next round with an edge and grit.

“This isn’t the worst thing for us,” Green said. “We get more reps together, more playoff-like reps, so it isn’t all bad.”

Curry said, “It’s a good test for us. … It’s a reminder of how hard it is to win at this level.”

Curry is braced for the bouncy flights. Sunday he even survived a Nikola Jokic bull rush, where the Joker attempted to become Curry’s 284-pound backpack. Some Warriors are new to that level of fun.

Jonathan Kuminga, for example. The rookie forward got his first taste of real playoff intensity Sunday. He seemed nervous at first, then chased away the butterflies with two sparkling sprints for fastbreak buckets. He will play a bigger role as the playoffs unspool, helping lessen the Warriors’ size and strength disadvantage.

So Sunday was Poole School and Kuminga College.

The going won’t get easier. Whenever the Warriors get ahead in a playoff series, the opposing coach and players always say they need to come out the next game and punch the Warriors in the mouth, effectively.

Nobody has sympathy for the seemingly punchable Warriors. TV play-by-play man Mark Jones commented Sunday on “all the contact Jokic has endured in this series.” That’s like sympathizing with Mike Tyson for the damage done to his fists by an airline passenger’s face.

The team’s reaction to Sunday’s loss is a good sign. It shows that the Warriors are part of the large group that does not feel sorry for the Warriors. Cookies, anyone?

Scott Ostler is a San Francisco Chronicle columnist. Email: sostler@sfchronicle.com Twitter: @scottostler