Asked and answered by MLB.com:
Since the advent of the dual Wild Card playoff setup in 2012, it hasn’t been necessary for the league to utilize even the three- or four-team tiebreakers.
Mathematically, it’s unlikely to be an issue this year.
But as we enter the next to last week of the regular season, it is, at the least, a mathematical possibility in the National League.
Our 2019 tiebreakers piece covers various scenarios like two-way division ties and three- or four-way Wild Card ties that could still happen. But we’re reserving this space for the ultimate October appe-tie-zer – the five- or six-way-tie possibilities still on the table.
Consider this your Chaos Compendium, albeit with a necessary disclaimer that the tiebreakers that follow are our own creation and not actual MLB protocol”