This year it's "How did they do on the road?"
In justifying Middle Tennessee State (with 1 Top 100 win) getting in over, for example, Virginia (8 Top 100 wins), the NCAA selection committee chairman said, "We looked at how they played on the road, and Middle Tennessee State performed very well on the road."
Two other times in the interview, to justify seeding or bubble selection, he mentioned road performance. (Never mind that the RPI takes this into account, probably too strong, IMO.)
As an annual resident of the bubble for four years, I'm sensitive to what the Annual Arbitrary Bubble Elimination Criterium is. Sometimes it's OOC strength of schedule, sometimes it's how you finish (strong/weak), sometimes it's RPI, sometimes it's the color of your uniform, sometimes it's whether your coach can use "certifiably insane" in a sentence ....
This year, it's "road performance". Good to know.