Josh Donaldson would announce his presence loudly each morning by blaring tunes from the Bluetooth speaker at his locker. Later, the reigning American League MVP would take the music with him to workouts and batting practice, where he'd offer tips and talk hitting with rookies and veterans alike.

Donaldson, the Blue Jays' all-star third baseman, set the tone from the moment he arrived at camp this spring. The team is counting on him, and other veterans, to maintain the rare clubhouse chemistry that was a big part of Toronto's breakout 2015 season.

"I don't think that happens everywhere where a team's superstar is so willing to help," said second baseman Ryan Goins, who's added a leg kick in his approach at the plate to mimic Donaldson's. "JD, (Jose) Bautista, Tulo (Troy Tulowitzki), Eddie (Edwin Encarnacion), they're all like that.

"The proof of it is in the pudding last year. You could feel something special in how we acted with each other. Everyone felt like the person next to them had their back."

For the first time since 1994, the Blue Jays open play as defending AL East champions.

While their post-season ended earlier than they wanted it to — they lost in six games to Kansas City in the AL Championship Series — the core of that group is returning for 2016, and they're closer than ever.

Donaldson has had a lot to do with that, continually fostering clubhouse chemistry by making everyone feel welcome.

He began one of his first days in camp by tossing a football around with newcomer Domonic Brown. Later he was spotted with Brown in the batting cages hours after workouts had ceased for the day.

"It was pretty impressive," manager John Gibbons said. "I hadn't seen anything like it before. One thing they do is they really help coach each other, and that's the ideal situation. You don't get that too often."

Toronto's core players saw each other frequently during the off-season. They met in Vegas for a UFC fight and convened at Bautista's for a onesie-themed Super Bowl party. Some even reported to Dunedin months early to train together.

Donaldson said he's a "big believer" in the chemistry the team has developed.

"Some people are for it, some say it's a non-factor but if you could have seen our clubhouse from the beginning of last season to the end of it you would definitely understand," he said.

"You have teams that just show up to the ballpark and you have teams where guys look forward to showing up and being around the guys. When you have that, when you have 25 guys on the same page, now it becomes fun and you start having success. The guys we have now and the ones we had last year, it's a special group."

"I'm excited to be back with the boys and cause a little trouble," he added.

Even players who weren't part of last season's team agree.

Canadian left-hander and former Minnesota Twin Scott Diamond, who signed a minor-league deal in November, was amazed at how quickly he felt included.

"I thought the Twins always had a tight knit group but it's not even comparable to this," said Diamond, who's since been relegated to minor league camp. "Usually there's separation between pitchers and position players and you don't see that at all here. That's the basis for a great team chemistry and they've got it."

Toronto opens the season Sunday in Tampa Bay with right-hander Marcus Stroman on the mound. The 24-year-old has made it clear he intends to fill the role of the staff ace left vacant when trade-deadline acquisition David Price signed a free-agent deal with Boston in the off-season.

Rounding out the rotation is R.A. Dickey, J.A. Happ and Aaron Sanchez, who beat out Gavin Floyd, Jesse Chavez and Drew Hutchison for the contested fifth spot. Marco Estrada (back) will start the year on the disabled list.

Roberto Osuna won the closer's role, centre-fielder Kevin Pillar is the lead-off hitter, Darwin Barney is the back-up infielder and Ezequiel Carrera cracked the roster as the fourth outfielder.

This season will be the first under the new front-office regime of president Mark Shapiro and general manager Ross Atkins, after the departure of popular general manager Alex Anthopoulos and president Paul Beeston. It could prove pivotal, with sluggers Bautista and Encarnacion set to become free agents at the end of the year.

The Blue Jays finished 2015 with 93 wins, their most since the 1993 World Series championship season, to win the AL East and break a 22-year playoff drought.

"We had a pretty good attitude last year and I think that started with Russell Martin and Donaldson — they brought some toughness and energy and a lot of focus," Gibbons said. "But yeah, we feel good. We've got that monkey off our back, to win a division, that hadn't happened in a long time. There's definitely a good feeling."