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."