Last July, Vladimir Guerrero Jr. arrived for Summer Camp in Toronto out of shape. He knew it, and his teammates knew it.

Not far removed from being baseball's brightest prospect with generational potential, this was an early threat to the 21-year-old's long-term success. Guerrero knew something had to change, so that's when this all started.

From then to now, Guerrero has lost 42 pounds and transformed his body. His fitness has been the talk of camp through the early days in Dunedin, Fla., and Guerrero was introspective on Wednesday when he thought back to the summer of 2020.

"For the last couple years, they knew I was coming here out of shape. I didn't prepare myself very well," Guerrero said through a team interpreter. "I felt like, at that moment, my teammates needed an apology from me. I just talked to them for a while, and the good thing about that is that they accepted my apology. Right then, they talked to me, they motivated me. You know what? It's in the past. Let's start over again and start getting ready."

That's no small number, but weight loss wasn't the sole focus throughout this process and shouldn't be the sole focus now. Weight, like a batting average or slugging percentage, is an important piece of the broader picture, but it doesn't tell nearly the full story. Guerrero also focused on his flexibility, and later in the process, building back additional muscle on his leaner frame.

This just isn't about looking good and playing well on Opening Day, either. This is about sustaining his talents through a full 162 games and all of the fatigue that comes along with the most grueling schedule in sports.

In Vlad's own words and through the eyes of others, this is the start of a new chapter for Guerrero.

How Vlad feels
As Guerrero began working out in the Dominican Republic in the offseason, one of the first tells was his clothing. Suddenly, a shirt that was tight at the end of the season was fitting a little looser. It's important to have these quantifiable benchmarks that you can point to and say, "This is progress." So Guerrero continued, encouraged by his teammates along the way.

The important part, though, is how this all translates and how Guerrero's improved fitness creates a better ball player for the Blue Jays. He tried to narrow it down.

"I feel quicker," Guerrero said. "That's the word to describe all I did. I'm quicker in all aspects of my game right now, especially running the bases, I feel great. Taking ground balls, before I would feel a lot of fatigue taking ground balls. Now I can say 50 or 60 ground balls and I'm still feeling good."

Defense has long been the question mark with Guerrero, and that question persists. Guerrero said all the right things Wednesday, expressing an openness to playing first base, third base and doing anything his club needed. Entering season three in the Major Leagues, this has always been Guerrero's mindset.

Regardless of which corner he spends the most time at -- it will be first -- Guerrero needs to improve. One of his main struggles coming up as a rookie was moving in on balls, when flexibility and balance got in the way of his quick feet and strong arm. That was on his mind as he made these changes.

"I work very hard on my legs, because I really wanted to trust my legs," Guerrero said. "Before, I couldn't trust my legs. I wasn't getting there. I wasn't getting to the ground balls, and of course at the plate, sometimes I wouldn't stay back enough on the ball. Right now, we are working very hard on that. I would say my defense is where I really improved most."

How the Blue Jays feel
Stretching back to Guerrero's time as a top prospect, you've heard the Blue Jays' front office mention the word "routines" year after year. With some hindsight, we better understand what that means now.

Routines are an engrained process. In a game of peaks and valleys, routines, especially when it comes to fitness, are a critical constant for a baseball player. The Blue Jays are very pleased with what they've seen on that front, because this looks like something that Guerrero is embracing over the long term.

"It's incredible to see the smile on his face, the shape that he's in, how his routine has developed and how it's become his own," general manager Ross Atkins said. "Every day this offseason, he's gotten better. He looks great. He's in a really good position and I'm really excited to see how that's going to impact every aspect of his game this year."

Manager Charlie Montoyo was thrilled when he saw Guerrero walk into camp. Montoyo will always have Guerrero's back, but he knows the realities of the past couple seasons. Now, like everyone else, he's seeing a new version of the young slugger.

"He's going to end up being, in my opinion, one of the best hitters in baseball over time," Montoyo said. "Just by being in shape and the way he looks right now, he's going to get there. I don't want to put that much pressure on him, but I really think that's what he can do. We all thought that's what he can do."

How his teammates feel
If there's one player on this roster who understands Guerrero's challenge, it's Rowdy Tellez. When the Blue Jays drafted Tellez out of high school back in 2014, he was larger than he is today and needed to make changes not just to his workout routine, but in his day-to-day life.

"That's really mature. That's a huge move," said Tellez of Guerrero. "You can even see the way he moves, the way he talks, his mannerisms, everything he does. He's very happy and very excited for the season because of the changes he's made. That's something you need. A Vlad that can be happy and excited and healthy and ready to move can be one of the dangerous players in baseball."

Tellez's first suggestion when Guerrero sought his advice was to cut out late eating. That's not easy for a ballplayer, either. By the time they leave the park at night, it could be 11:30 or midnight, and after playing in front of tens of thousands of screaming fans, you're not falling asleep right away. Guerrero has changed his postgame routine now and stuck to it, which is helping.

Tellez also sees the version of Guerrero that others don't, and the work that's gone into all of this.

"I feel Vlad is a very misunderstood person," Tellez said. "That's just my opinion. I don't think people really understand how hard he actually works, and he works hard. This offseason just shows you that this guy is going to bust his butt to be the best he can be."