New schedule > old 50% of your schedule in division.
Strong disagree. The majority of fans SAY they want to see everyone in the league, and say that making interleague rivals be division rivals is good for business. But attendance numbers don't reflect that.
Fans aren't SPENDING to see everyone in the league. They show up for 3-4 games/series with star power -- your Crosby/Ovechkin or Shohei Ohtani visits -- but then show up LESS for everyone else who has to visit in order to get the star teams visiting. You're trading 10 for 5.
I actually ran numbers over a decade for hockey we argued H/A with every team. There's just more teams that don't draw road crowds in the other league/conference than teams that draw crowds for games that MATTER LESS in the standings. (And a third of the league is close to selling out regardless). It's just BAD USE of inventory.
(I also have yet to find a single person in a two-team market who went to "the other team's" stadium just to see a visiting star player. Every star player visits New York, Los Angeles, Chicago, the Bay Area and the DMV. I just can't take that argument seriously when a third of the league has the option and don't take it).
And of course, we can use the Astros switching leagues to show that their Interleague series averaged 5,000 fans more per game than since they've both been AL West (and Houston is A LOT better now, the Astros were losing 100 games the last few years in the NL).
You're not going to make Marlins/Rays a legit rivalry with radical geographic realignment in MLB, unless both teams are good at the same time or dudes start drilling each other. And that can/does happen regardless of a map. It's the STAKES that make the rivalry. Texas/Toronto got heated for a bit with Joey Bats bat throw and Roughned Odor's punch throw. They aren't close on a map, but those stakes were high.
There's far more to LOSE by radical realignment. The "Bragging Rights" kind of series are about two fan bases arguing for an entire year over who's better because there's no way to settle it until the one time we play, and that series shapes the argument for the rest of the year. Same division, same schedule: there's really no bragging rights when it's six series spread out of six months and the standings tell you who's better by June.