Going into October, the Yankees made clear their plan to ride their bullpen in pursuit of a World Series title. What was unclear was how much their plans would contrast with the rest of the league.

The Bombers have won four of their five games and have an impressive 1.95 team ERA. They’ve yet to allow more than four runs in a game. However, of the 46 innings they’ve pitched thus far, 24 have come out of relievers compared to just 22 over five starts. That’s an average of about 13 outs per start without having used an opener or designed a full-fledged bullpen game.

This appears to be the intention with good reason. The Yankees were short on starters and had five of the top relief arms in the game, so riding that handful makes sense. Their top arms, with perhaps the exception of Chad Green, were able to rest in September with eyes towards a busy October.

But none of New York’s counterparts have followed suit. The Astros, Nationals and Cardinals, three remaining teams outside of the Bronx, have each relied upon their starting pitchers. Headlines have run about the return of the starting pitcher to October. These three teams have wagered their World Series hopes on 3-4 arms that can carry them most of the way.

To spell that out further, here’s how the Yankees compare to their postseason peers in innings given to starting pitchers.

Note: J.A. Happ is included as a Yankees reliever, while the Nationals’ starters and Miles Mikolas’ respective bullpen appearances count towards the starters’ innings. Happ doesn’t appear to be a starter in the postseason.

IP by SP (%)Longest Start5+ IP StartsSP ERARP ERA
Yankees47.86 IP2/52.051.88
Astros67.78 IP5/73.584.42
Nationals77.37.2 IP9/92.294.42
Cardinals68.57.2 IP6/82.594.84

Whether through their basic rotation or throw-day outings from starters, the other three remaining teams have been steadfast in relying on a more traditional path. This has flown away from expectations and the trends of the past few postseasons.

That’s with good reason; The Astros have three of the better starters in all of baseball, and the Nationals boast the best quartet of any postseason team in addition to a lackluster bullpen. The Cardinals, meanwhile, have found their bullpen unsteady in postseason action, while their rotation has stepped up. All four teams have had some semblance of success in their methods, or else they wouldn’t still be standing.

Of the other postseason teams, only the Twins and Rays came into October with a similar approach to the Yankees. The Twins were doing so out of necessity with multiple starters unable to go. The Rays, meanwhile, had Tyler Glasnow and Blake Snell still working their way back to full strength while sporting a bullpen with more depth than the Yankees and perhaps as much talent.

No team (as far as I can tell) has won the World Series with a majority of their innings coming from non-starting pitchers. The closest parallel is the 2015 Royals, which had traditional starters and as ferocious a bullpen as the Yankees. They got just over 58 percent of their innings from starters en route to the title. The Indians a year later came close, but their bullpen wilted in the final long series. The 2009 Yankees are the last World Series champion to make it through the postseason with just three traditional starters.

The Astros and Red Sox of the past two years have paved a different road by using starters on their throw days as a consistent part of their strategy. The Nationals this season have followed that more aggressively and they’re a win from the Fall Classic.

The Yankees could have gone a different route if they’d bought at the deadline or been more active in the starting pitching market in free agency. Still, they’ve gotten this far on the strength of the game’s best bullpen and there’s no turning back in 2019. Thanks to a quick ALDS and a lineup that matches the Astros’ nine in total depth if not talent, they’re in a position to win in a new-fangled way.

The Yankees’ clash with Houston and potentially with the Nationals or Cardinals makes for ideal October theater. Two competing organizational philosophies and builds vie for superiority, with a trophy on the line for the winner and a winter rethinking one’s priorities for the loser.

A contrast of styles is something to behold, making baseball worth tuning into as the opposing teams don’t mimic each other and actually appear to exist in a separate phylum of sport. Baseball seems to head for a world where the line between starters and relievers is permanently blurred in an all-too-efficacious squadron of interchangeable pitchers. For now, the differences between teams give a welcome respite from that eventuality.

But there are also ramifications for the current bullpen strategy. If the Yankees win, it validates the way they’ve built the roster and could lead to a further prioritization of bullpen firepower. A loss in this series makes the addition of a workhorse to the front of the rotation more of a necessity than a luxury to consider, as critics of their idle deadline swarm. In that way, more than just a title is on the line in the coming days and weeks.