BOSTON — The Gordon Hayward hype train officially departed North Station on June 5 when Danny Ainge, less than a month removed from his team’s disappointing postseason exit, gushed about, “anticipating great things,” from Hayward based on his early offseason workouts at the team’s practice facility.

Since then, that train has become a runaway locomotive, with members at every level of the Celtics organization raving about Hayward throughout the offseason. That train seemingly rumbled off the MBTA tracks outside the Auerbach Center Wednesday and smashed through the walls of Red’s House when Enes Kanter doubled-down on his already bold proclamation that Hayward should be eyeing a return to the All-Star game this season.

"He’s back. He’s 100 percent back,” said Kanter. "He’s going to shock the world this year.”

It’s 100 percent fair to be skeptical. Even as Hayward endured a second surgery on his ankle last summer, there was no shortage of ballyhoo in the ramp to the 2018-19 season — in part because the Celtics were also adding a healthy Kyrie Irving to a team that came four minutes away from a trip to the NBA Finals.

Kanter, regarded as a Hall of Fame locker room guy, also has a long history of talking up his teammates. Heck, he raved about coach Brad Stevens’ basketball skills last month. So if you want to be leery of Kanter’s proclamation, we get it. But know that he’s also practicing what he preaches.

"When Coach puts us in 5-on-5 [scrimmages during training camp], I always try to sneak on Gordon's team,” Kanter told NBC Sports Boston after Wednesday’s morning workout. "When I go against him I’m like, ‘Ugh.’ He’s good, man.”

It’d be one thing if Kanter was the only person gassing up Hayward. But this has been universal. Whispers in the ramp to camp were that Hayward was easily the best player in Boston’s informal scrimmages, though it should be noted that players like Kemba Walker and Jayson Tatum were limited participants while recovering from the World Cup grind.

At the very least, Hayward has increased his odds of hitting the ground running this year with his summer efforts.

Hayward put his San Diego residence on the market and bunkered down in Boston this offseason. He spent most weekday mornings working out with the Celtics’ training staff at the Auerbach Center and his dedication to staying close encouraged fellow teammates to do the same.

Stevens, never one to overhype his players, has routinely noted how Hayward has positioned himself for success with his offseason dedication. Asked Wednesday how Hayward has looked at the start of camp, Stevens responded, "The investment has been well-documented over the summer. And you can see it. You can see it.”

That’s about as high of praise as you’ll get from Stevens. Which leads us to believe that, when there’s this much smoke, there’s usually fire (kind of like when everyone kept saying that Irving was definitely bound for Brooklyn).

It’s absolutely fair to want to see it. The Celtics have kept nearly all of their camp activity behind closed doors to this point, with media members seeing only limited shooting drills at the end of morning sessions the past two days. So we’ve been left to get scouting reports from Hayward’s teammates. And, considering there are eight rookies in camp, you can take their views with a grain of salt.

Asked for his opinion of what he’s seen of Hayward, rookie Vincent Poirier, an imported French big man, said simply, “He looks like he never got injured,” then raved about Hayward’s full-throttle mentality in camp.

A real glimpse will come soon, at least by Sunday’s exhibition opener against the Charlotte Hornets. It should be evident quickly whether Hayward is truly playing with the same sort of confidence and ability as the one the Celtics lured away from Utah on a four-year, $128 million contract in the summer of 2017.

Kanter insists his bullishness about Hayward goes beyond just how he’s looked on the court.

“It’s his leadership,” said Kanter. "He already had a lot of confidence in himself but he seems so comfortable out there. Because I played against him last year and then, what I've seen the last two days, how he plays, how he leads, it’s just very special.”

Kanter admitted he could tell Hayward wasn’t quite himself last year, especially early in the season. The two players were teammates in Utah and Kanter saw the early stages of Hayward’s evolution into an All-Star.

Now he wants to see him get back to that level and believes he will.

“He's the type of guy that not only makes himself better, he makes everybody else better around him,” said Kanter. "That’s what makes him really special.”

For his part, Hayward said Wednesday that, “The body feels 100 percent.” Earlier in the week he noted how training in Boston allowed him to build the sort of momentum that had been sapped by the second surgery last summer.

"I have been through a lot — and just in the last two years — and it is exciting to have that full offseason where I can train and get back to what I’m used to doing and not worry about my ankle or health or anything like that,” said Hayward. “Now having two years with the guys and the staff and building relationships and different things like that, it’s definitely better in that regard, too, so certainly I'm looking forward to this upcoming season and I’m ready to get it going.”

Hayward is scheduled to earn $32.7 million this season. A return to All-Star form could leave him with an interesting dilemma next summer, as he has an early termination option. Hayward is set to earn $34.2 million in the final year of his Boston deal but could opt out and seek a more bountiful max-salary deal, now with 10 years of NBA experience.

The Celtics will happily cross that bridge if it means Hayward gets back to his previous form. Getting him there could be the biggest key in Boston outkicking its already tempered expectations this season.

If he doesn’t, the Celtics have some tough decisions of their own about how to move forward. The team has a glut of talented wings and both Jaylen Brown and Jayson Tatum could soon command big paydays. Hayward’s bulky salary could make it enticing for the Celtics to make a big in-season trade — maybe allowing them to jump into the fray if Bradley Beal becomes available, or any other disgruntled star that hits the trade market.

For now, the Celtics would rather just get the Hayward they had before his gruesome ankle injury. They want the Hayward that everyone has been hyping all offseason.

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