For more than a decade, from coast to coast, they rose from urban cores and suburban sprawl alike, feats of architectural perfection that defined the fan experience in Major League Baseball – in perpetuity, it seemed.

The great ballpark building boom that spanned the 1990s and into the millennium’s first decade was a welcome correction from the multi-purpose mausoleums that dotted the landscape in the 1970s. And the billions and billions of dollars expended – much of it coming from taxpayers – to create a more intimate setting felt like a permanent fix.

Yet as the industry discovers the appetite for live baseball may be shrinking, a third wave of stadiums are gradually coming online, revealing franchises' desire to further shrink the ballpark - be it new or already existing.

“The Camden Yards-era ballparks were fitting the bill,” Oakland Athletics president Dave Kaval says of Baltimore’s innovatively retro stadium that opened in 1992. “But that was 20 years ago.”

'JUICED' BASEBALLS? Scientists may have found the problem

PHILLIES: Could Kapler be fall guy if team doesn't fulfill expectations?

Kaval is charged with finding a new ballpark for the A’s and the club has progressed significantly on a waterfront project at Howard Terminal, near Jack London Square. Major hurdles remain, most notably Oakland City Council approval of a complicated deal centered on a 34,000-seat stadium.

Since 1989, every major league club save for the A’s and Tampa Bay Rays have inhabited a new or significantly renovated stadium. The Rays’ failed attempt at building in Tampa’s Ybor City aimed for a ballpark with 28,000 seats; they have already reduced capacity at Tropicana Field to 25,000.

The Atlanta Braves and Texas Rangers, leaning significantly on public funding that came without taxpayer referendums, ditched parks built in the 1990s for smaller digs framed by the game’s new revenue engine – mixed-use developments at least partially controlled by the team. The Braves are in their third season at SunTrust Park (capacity, 41,000, replacing Turner Field’s 53,000) while the Rangers in 2020 will open Globe Life Field, a retractable-roof facility that will seat 40,000 compared to its predecessor’s 49,000-seat capacity.

Others are on the way.

The Los Angeles Angels are negotiating with the city of Anaheim to fix up 45,000-seat Angel Stadium (last major renovation: 1997) and develop the parking lot; the club has floated the possibility of moving the team to Long Beach, where the ballpark footprint would be significantly smaller.

And the Arizona Diamondbacks can escape their Chase Field lease in 2022 if they build a new stadium within Maricopa County; the team gained that right by agreeing to drop a lawsuit claiming the county owed $187 million in repair and renovations to Chase Field, which opened in 1998.

Failing that, the Diamondbacks could follow the lead of the Rays, Cleveland Indians and others, and simply transform their 48,000-seat stadium into a smaller venue that reflects an environment where attendance across MLB is projected to decline for a fourth consecutive year, mirroring trends in several sports.

“We are definitely keeping our options open as it pertains to remaining at Chase Field,” Diamondbacks CEO Derrick Hall said in an email to USA TODAY Sports. “We have said for years that our ballpark capacity is far too large.

“In a market like ours, it is not realistic to believe we can fill Chase Field on a regular basis.”

For the Diamondbacks, A’s and perhaps a significant number of clubs that may replace – or revamp – their Camden Yards-era parks, finding the sweet spot of atmosphere, accessibility and inclusion will be paramount in a sport with an aging and occasionally alienated fan base.

Less is more

It seemed like a good idea in the 1960s and ‘70s: Build massive, multi-purpose stadiums for your local football and baseball team. Lay down some AstroTurf – it doesn’t even need water! – and your facility is suddenly a year-round destination for sports, concerts, religious revivals or monster truck pulls.

But as the 1990s dawned, Major League Baseball’s 26 stadiums were aging and almost always half-empty.

In 1990, the year before Chicago’s new Comiskey Park kicked off a wave of 21 new or heavily renovated stadiums in 20 years, the average major league park seated more than 54,000 fans.

Eleven teams had capacities of at least 57,000, with football-inspired expansions creating enclosed ghost towns in cities like San Diego (59,000-seat capacity), San Francisco (62,000) and Anaheim (64,000).

In the median ballpark, 53% of seats were empty.

By 2009, when the Yankees and Mets rolled out new stadiums in New York, the wave of new ballparks lopped nearly 20% off MLB’s ticket inventory: Average stadium capacity was 44,000, and the median club enjoyed a 64% occupancy rate.

Since then, the Twins, Braves and Marlins rolled out newer, smaller stadiums. So far in 2019, teams are playing to 66% capacity.

But MLB’s attendance took a 4% hit in 2018 and is on pace for another dip this year. As pace-of-play and other concerns roil the game internally, and bottomless entertainment options threaten it externally, it’s easy to imagine other markets following Cleveland’s lead: Shrink the stadium.

With Cleveland suffering a population decline and the 2009 recession hitting it particularly hard, the crowds that jammed then-Jacobs Field beyond its 43,000-seat capacity in the late ‘90s were unlikely to similarly fill rebranded Progressive Field.

So before the 2015 season, the club chiseled away.

After surveying its fans and season-ticket holders, unused suites were converted into a two-story indoor-outdoor family area with baseball-related activities. The right field corner was turned into a “social space,” with a large outdoor bar and gathering area. The right-center field area opens up to the city around it.

Nearly every change in the refreshed 34,000-seat park was geared toward a nebulous concept viewed as crucial to resuscitating the ballpark experience: Engagement.

“It’s incumbent on us to create an environment in ballparks to give people compelling reasons to make that trip,” says Alex King, the Indians’ senior vice president of brand and marketing. “There are no barriers for fans to engage in our game in a living room.

“In the ‘90s, it was creating intimacy, it was the architecture. I think those changes were fantastic. And now, how do we make those micro changes – the social changes, the experience. That’s the regular work the industry needs to do to make sure that experience is compelling enough to come out.”

Kaval has racked up a few miles in service of that mission. He’s visited all 30 ballparks, as well as stadiums overseas, and as president of Major League Soccer's San Jose Earthquakes played a central role in developing 18,000-seat Avaya Stadium.

The A’s are aiming for distinct in their desired home, hiring a Danish firm to design a stadium that would include a rooftop park that encircles the stadium. A panoramic view of the bay – not visible from stadium seats for myriad reasons – would be the catnip to encourage fans to circulate throughout the game.

For now, they’re using antiquated Oakland Coliseum as a petri dish for that concept, selling monthly passes to “The Treehouse,” an area above left field with 1,500 seats and nearly as many libation options. The idea is to roam during the ballpark and enjoy “multiple experiences,” Kaval says, during each game.

Yet for all of Kaval’s globetrotting, his vision of a new stadium is largely driven by a development just a few miles from home.

“The iPhone has ushered in a whole new era,” says Kaval. “We just found the fans wanted – younger fans, Millennials and Gen Zers - experiential things they can show on their Instagram, their Snapchat. Live sports are changing. Entertainment is changing.

“When we’re thinking of deploying hundreds of millions of dollars for infrastructure, we need to stay with the times. Stadiums are iconic gathering places. You have to do it in the context of the way people are experiencing entertainment today.”

It all sounds a bit like a stock-art photo touting a new mixed-use development come to life, with baseball subbing in for trivia night or ax-throwing as the backdrop for young and old alike to sip IPAs and preen for the ‘Gram.

Yet, the industry also knows it must be wary of the price tag – to build the stadium and access it.

Access is everything

Baseball has five franchises essentially invulnerable to sagging attendance – the Red Sox, Cardinals, Cubs, Yankees and Dodgers. All have sold at least 87% of their 2019 ticket inventory and drawn at least 2.6 million fans every season this century.

For most of the 25 other franchises, team performance, the economy and the limitations of their stadium can have a far greater impact.

Right now, 15 teams are on pace to draw fewer fans than a 2018 season that saw a 4% overall drop; with September likely to mirror an ugly April at the gate, it wouldn’t be surprising if up to 20 teams’ attendance declined.

Not that some haven’t tried.

The Tampa Bay Rays sold 5,000 tickets to five June home games for $5, selling out the allotment for just two of the games. After announcing their intention to explore playing half of their home games in Montreal, the Rays – who declined comment for this story – held a $2 flash sale for a three-game July series against last-place Baltimore.

The San Francisco Giants – suffering through a 17% drop at the gate in the first year of an expected rebuild – also offered $5 tickets during a one-day flash sale.

With the in-game experience so key to building fan loyalty, wouldn’t it behoove teams to fill up empty seats at discount prices?

Perhaps not at the expense of undercutting season-ticket holders.

“Is value important? Certainly. But it’s not a silver bullet in terms of a single solution to ensuring we have the attendance that we want,” says the Indians’ King. “Our season ticket holders are investing a significant amount in us and shown a lot of loyalty. We really value that and want to ensure that as the lifeblood of our organization, we protect the investment they’ve made.”

On the other end of the spectrum, smaller, successful stadiums can breed ticket scarcity, tempting teams to increase prices and potentially squeeze out fans of lesser means.

The A’s will be the only game in town on that side of the bay, with the Warriors gone and Raiders going. Proximity to Silicon Valley means no shortage of wealth – corporate and otherwise – to tap.

But will 34,000 seats be enough for fat cats and working families?

“Inclusiveness and making sure we have product available to fans at all income levels is critical,” Kaval insists. “The family of four has been priced out of (a lot). I think baseball can own that spot where just regular folks can access affordable options.”

Says the Diamondbacks’ Hall: “We need to check ourselves constantly to ensure affordability for fans. We base this on history and market demands. A new stadium should not be a launch pad for ticket prices if previous levels are already deemed appropriate.”

Who’s footing the bill?

The A’s are already navigating perilous waters. Their proposed stadium deal would allow them to recoup construction costs by developing the land on their current Coliseum site, no small ask given the Bay Area’s ongoing housing crisis.

Alameda County agreed in April to sell the A’s its share of the Coliseum site for $85 million, while the club is negotiating for the other half with the city of Oakland, which desires to bake affordable housing, environmental mitigation and living-wage jobs into the project.

In a cruel twist, Alameda County is expected to use money from the A’s to pay off debt on its 1995 renovation of the Coliseum for the Raiders – widely considered one of the worst financing deals in stadium history, particularly for a team that stayed just more than two decades, anyway.

Though the Rangers’ and Braves’ new stadiums show the public-funding spigot may never be turned off – particularly if taxpayers have no say – municipalities may be warier to fund the palaces of billionaires. While the Braves’ park got funded essentially behind the public’s back, it also cost Cobb County politicians their jobs.

More than $12 billion in public money was spent on stadiums across all sports in the first 15 years of this century, that on the heels of billions more spent to fund many of the ballparks in the Camden-inspired wave.

It would be unsurprising if public sentiment sounded something like, “Didn’t we just buy you a stadium?”

That won’t stop teams from trying – particularly when the bar for entertainment only seems to rise.

“If you’re going to come out to the park,” says Kaval, “it has to be special, it has to be different.”

And in the future, probably a lot more cozy.