Wait till Arizona switches to the Central Division after Seattle starts play. Look at Arizona travel schedule
Dallas and Colorado will be their closest division but still have Minni, Chicago, and Winnipeg to the north and St Louis and Nashville to the East. Yikes,
You're right Nashville should be the in the East, but for admittance to the league this agreed to perennial western team.
Tampa and Florida should be in the Metropolitan instead of he Atlantic (northern division). Columbus and Pittsburg could logically be in the Atlantic. But the the the three teams in New York/Jersey and Pittsburg wanted a cozy travel schedule, and they have more pull in the alignment talks than other teams.