SANTA CLARA — On what can be equated to the first day of school for Kyle Shanahan, 100 percent of his 49ers players were in attendance to kickoff San Francisco’s offseason program Monday at Levi’s Stadium.

There’s a laundry list of news and notes to go over including DeForest Buckner looking noticeably bigger, NaVorro Bowman’s repaired Achilles, Carlos Hyde welcoming Leonard Fournette as competition at running back and whether the 49ers plans have changed at cornerback after releasing Tramaine Brock.

But the overwhelming theme in the South Bay is that this football team will be operating with higher expectations. Last year’s shotgun marriage between Chip Kelly and Trent Baalke, and their careless lack of communication, is no longer standard operating procedure.

Teammates are expected to get on each other in meetings and the practice field. Accountability is no longer just a buzzword. If certain players don’t comply?

“It’s probably not going to be the place for you,” Shanahan said. “When the players hold each other accountable, when the players have a certain standard that they go to whenever a guy is slacking that the players get on that guy before the coach does, that’s when you have something special.”

One feeling in the air is certain: This isn’t Jim Tomsula. This isn’t Chip Kelly. Kyle Shanahan, however chill and relaxed his demeanor may seem, has brought a heightened sense of awareness to a locker room that desperately needs a purpose. Steve Kerr and the Warriors call it appropriate fear. It’s an actual atmosphere. Cutting players such as Torrey Smith, Antoine Bethea and Brock for his domestic violence arrest has opened the eyes of Baalke’s holdover players on the roster.

I get it. It’s Day 1. Playbooks have just been handed out. All the new players are still learning each other’s names. These first two weeks will be mostly about conditioning and bonding. There’s no way to predict win totals yet — even though I asked Brian Hoyer if 8-8 seems achievable.

The clout Shanahan earned engineering the No. 1 offense in the NFL — Super Bowl collapse or not — has been recognized by players. Hyde, who is sadly on his fourth head coach in four years, noticed something right away about Shanahan: confidence. The 49ers don’t have some desperate retread manning the sidelines; Shanahan was almost non-arguably the most qualified candidate on the market. GM John Lynch himself once called his head coach cocky, in a good way, on one of his FOX broadcasts. Shanahan carries himself this way and the players became immediately aware.

“To have a coach who thinks he’s the best coach in the National Football League, to have everyone around the facility thinking they’re the best at the best at their position,” Hyde said, “to me, that’s a great atmosphere.”

The goal, over time, is for the San Francisco 49ers to adopt this confidence on the field. Easier said than done, but Shanahan has the proof his coaching style can be prolific. Matt Ryan, Robert Griffin III and countless other players were able to shatter expectations because of the confidence Shanahan instilled in them personally, and the offense as a whole. Pessimism won’t be tolerated, and it’s likely players who gave off that vibe in pre-draft interviews were docked on the draft board (which still has yet to be completed, according to Shanahan).

This is not the last we’ll mention it, but Kelly’s laissez-faire culture from a year ago was probably his undoing. Meanwhile, Shanahan’s demanding of more player accountability could be a reason San Francisco goes 7-9 next season. The 2016 49ers were poorly constructed by Baalke, but there were deep-rooted problems, problems Shanahan is trying to change rapidly just by building relationships. In the midst of a 13-game losing streak, this football team remained relatively tight, meaning not enough people were enraged with the outcome every Sunday. Nobody wanted to hurt each other’s feelings. Joe Staley understands conversations will have to get a little more awkward this year. You have to be willing to temporarily hurt a feelings teammates to grow a foundation.

“Things needed to change. You kind of need to look inwardly,” Staley said. “Get more comfortable with being uncomfortable. At the same time, it’s not something you out and force.”

That’s the nail on the head and the line Shanahan will have to balance as he brings this team closer together. Get comfortable with being uncomfortable — because that’s truly the only way a football team can grow. And make sure it’s not forced. Whereas Kelly and Baalke avoided problems, this new regime seems willing to tackle them head-on.

All of this is really just Culture 101. Lynch and Shanahan are at the top of reestablishing it, but they obviously won’t be able to do it alone. That’s why you have leaders like Hyde, who said he’s watched all of the Atlanta games on his own. That’s why you have Bowman coming into April with a different mindset than he has in previous seasons.

“I’m hungry,” Bowman said. “I’ve been out of the game since Week 4. Any accomplishments I’ve had before none of that matters. I’m really back to proving myself.”

Reality sunk in when players watched film cut-ups of the Atlanta Falcons Monday morning. Shanahan is going to exhaust most of his time putting players in a position to win football games. He’s not going to be some inherent motivational speaker when addressing the team. Players of all ages — from a second-year pro like Buckner, to an 11-year veteran like Staley — will be asked to do more this season.

This is not an overnight experiment. There will be trials and tribulations for a first-time head coach to conquer along the way. With that being said, all observations indicate this as a solid Day 1 down in Santa Clara.