In Tom Verducci's new column on realignment, we see that some NL Central owners have been a little fussy about playing in a six-team division:
NL Central owners privately have been complaining for years about the inequity of playing in a six-team division (as opposed to only four teams in the AL West), and that grumbling has increased with the ownership change in Houston. The Astros have no natural or regional rival within their division -- just as the Rangers have no such rival in the AL West. Pairing them in a division makes sense.
What's unclear is just whom is doing the grumbling? The other five owners, or the Whooping Cranes?