Before Friday's 8-3 loss against the Tigers at Joker Marchant Stadium, Mattingly said he has been invigorated by the youthful competition.
"This is a teaching camp and a development camp, and it has actually been really exciting for me,'' Mattingly said. "So far, this has been one of the most exciting years I've ever had. This is about being part of something that we're building. We had a good group of core players, but we didn't have any sustainable pitching. We were putting band-aids on it for a few years. It was time for a transition.
"It just feels really good what we're doing. I think it will be sustainable long-term for the Marlins, and I hope I'm here to see it all the way through.''
Offseason headlines weren't about the Marlins' future.
They were about the painful breakups.
Giancarlo Stanton to the Yankees.
Marcell Ozuna to the Cardinals.
Christian Yelich to the Brewers.
"There are some markets out there that can fix things by throwing money at a problem, but that's not how we can or will operate,'' Mattingly said. "[Owner] Derek [Jeter] and his group have a plan and they've created continuity through the whole organization. We're going to build this thing from the ground up. There's a connection with our whole Minor League system.
"Even the organizations that can go for it in a big way, like the Dodgers and Yankees, they are intent on building great systems. I think everyone would rather do it that way because you build a base. We're not going to be able to go get every big free agent, but hopefully we're going to have nicely developed players coming to us every year.''
There already has been an infusion of young outfield talent, such as Lewis Brinson (acquired from the Brewers in the deal for Yelich) and Magneuris Sierra (acquired from the Cardinals in the Ozuna deal).
"Brinson is very polished,'' Marlins left fielder Derek Dietrich said. "He looks professional and handles himself like a professional. Sierra can straight out fly and he's so silky smooth in the outfield. We just need to make them feel comfortable and their talent will take care of the rest.''
Rated by MLB Pipeline as the Marlins' No. 1 prospect, Brinson said he is unaffected by the low expectations assigned by outside observers.
"People can keep writing us off, but we have a great future,'' Brinson said. "We can't control other people's opinions. My opinion is we've got one of the most athletic outfields around with speed and great instincts. I don't think we should let anything drop out there.''
Mattingly said he's eager to watch the organization's athleticism and youth.
At the same time, he knows its development will require time and patience.
"The one thing you realize as a manager is it's out of your control,'' Mattingly said. "As a player, you can make a play or get a hit, affect the game in some way. As a manager, you can affect it in the negative with a bad decision. You make good decisions and it's the players who did a great job.
"The biggest thing as a manager is you've got a group of people you're responsible for and a group of guys you want going in the right direction. You're overseeing all of that. I'm excited by what I'm seeing so far from our young guys. I think they're going to grow into something special.''