Major League Baseball changed the tie-breaker rules determining home-field advantage when the Houston Astros joined the American League this spring, but failed to announce it to the public, Susan Slusser of the San Francisco Chronicle discovered Tuesday.
The first two tie-breaker criteria -- 1) record in head-to-head games and 2) record in intra-division contests -- remain the same, but because there are now an even number of teams in both leagues, MLB decided that the Astros' move to the AL dictated that the third tie-breaker criterion be changed to overall record in intra-league games.
In seasons past, the stipulation called for a comparison of the last half of intra-league games, not the full season. That has now been made the fourth tie-breaker.
The reason this is important is that the Oakland Athletics and Boston Red Sox may need to use all four criteria to determine home-field advantage should they finish with identical records -- they're now one game apart -- and meet in the postseason. It could potentially be a factor in the very tight NL Central race as well.
The two clubs split their head-to-head contests this year, and are separated at the intra-division level by just half a game. That means there are still four scenarios in play that would lead to the third tie-breaker being employed, per the Chronicle.
Of course, a whole host of things have to happen over the next few weeks in order for any of this to happen, but it's good to know what the actual rules are just in case.