The Dawn of the Super Bullpen Era and the Pitching Trend That Wasn't

Everyone knew what was on the line in last year's World Series: a trophy, a parade, bragging rights for a long-suffering fanbase. What nobody realized at the time was that the Kansas City Royals and New York Mets were also playing to determine Major League Baseball's new prevailing pitching strategy.

The teams' pitching staffs were inverses. The Royals relied upon their devastating bullpen, limiting their rotation to the fewest regular-season innings of any American League squad. The Mets, meanwhile, were one of two teams to milk more than 1,000 innings from their starters. The Royals won, and the rest of the league has since spent the winter seeking their own proverbial end-game cheat code. Hence the New York Yankees entering the winter with two closers and exiting with three, the Boston Red Sox and Houston Astros following suit, and ditto for the Baltimore Orioles, arguably the movement's now-forgotten progenitors. The St. Louis Cardinals signed a reliever literally nicknamed "The Final Boss."

Perhaps those teams conceded that following the Mets' blueprint was out of the question—it's easier to explain biocentrism to a grade-school kid than to acquire multiple young, Cy Young-caliber starters—so they took the easier route. But consider it a sign of the times that the Seattle Mariners weren't declared the clear winners of a trade that sent out a 26-year-old setup man with a high-effort delivery for Wade Miley, a league-average starter on a cheap contract. Or that the Arizona Diamondbacks added two All-Star starters to the National League's second-highest scoring offense without being upgraded to certain-contender status by the analytical community.

The rise of the oft-mocked Royals and their bullpen means yesterday's stupid is today's smart. Whereas investing in the tail-end of a pitching staff used to be considered a fool's errand, these days it's an approved strategy of the intelligentsia. The reasoning is straightforward: starters cost more than relievers, yet most of them are ill-equipped to face a lineup more than twice in a game. Rather than leave a fatigued or exposed starter out there too long, the new hotness is to insert a reliever earlier than what used to be socially acceptable—and, as a consequence, lower the threshold on what makes an acceptable starter.

Religious-like adherence to the times-through-the-order penalty—the notion that each time a hitter sees the same pitcher in a game he is that much more likely to figure him out—is the kind of tradition-eschewing practice that sieves the genuine iconoclasts from the pretenders. On paper, the whole thing makes sense. Why wouldn't you put a fresher arm out there before the other team can jump on your non-elite starter? But there are issues that have sparked plenty of debate about the strategy's merit. To wit, the potential that the times-through-the-order penalty may or may not have more to do with pitch counts than repeated matchups.

One of the other concerns about the super-bullpen strategy is sustainability. The old-timey analytical take on relievers held them as fungible quantities due to their inherent fickleness in health and performance. The Royals' bullpen, the one that seemingly serves as the inspiration for most clubs, hasn't been immune: they lost Luke Hochevar (who recorded a 1.92 ERA and more than a strikeout per inning in 2013) to Tommy John surgery for the 2014 season, and then two-time all-star closer Greg Holland to the same operation last year. The Royals were able to replace both, obviously, but it wasn't necessarily due to genius or foresight. Wade Davis pitched well in his previous stint in the bullpen, but nobody expected him to become an unstoppable force when the Royals re-inserted him there before the 2014 season. Likewise, there was no reason to bank on Ryan Madson staying healthy last season after he'd missed the previous three campaigns. Both low-probability scenarios played out in the Royals' favor. And because they did, the Royals' standing among their peers improved from punchline to trendsetter.

The Diamondbacks, taking the opposite tack, are hoping to make the same transition in the coming years—at least in the eyes of the league. No team last season, not even the Royals, had their bullpen throw more innings than the D'backs did. Yet while the rest of the league headed in one direction, general manager Dave Stewart went the other way, ensuring his club wouldn't repeat its feat. First he signed Zack Greinke to a six-year deal worth more than $200 million, and later he traded a prospect horde that included last June's no. 1 pick Dansby Swanson for Shelby Miller—two old-school gestures from a team that has embraced the label.

Anecdotal evidence on either side doesn't go a long way in determining whether the D'backs should be mocked or applauded for their direction. The White Sox were the other team to top 1,000 innings from their rotation, and they won fewer games than the Diamondbacks did. Contrariwise, the Rays, an early adapter of the bullpen-heavy strategy, ranked 20th in bullpen ERA—and remember that they a) play in a pitcher-friendly park and b) fielded an elite defense, both of which ought to suppress their ERA. Perhaps you can reason that the Rays' rotation pitched better due to its reduced usage, but that gives way to a different argument that goes something like this: if using relievers more can help starters perform better and stay healthier, then aren't relievers (particularly those not used to heavier workloads) going to perform worse and get injured more?

There's no easy way to answer that, either. See why this is a controversial topic? For example, you may wonder how the top bullpens were employed. If you go by ERA, the top-five units ranked 10th, fifth, 22nd, 29th, and 11th in innings—a spread that provides no real consensus on what works best. Success appears to hinge more on personnel and context than on any set strategy.

Therein lies the rub. Baseball has the nasty habit of looking for one correct answer to every problem, thus the oversaturation of "right way" proclamations about everything in the sport: from playing the right way to rebuilding the right way and everything in between. Baseball's follow-the-leader mindset—if it worked for them, it will work for us!—leads to these kinds of winters, where it seems like the paradigm has shifted and only the Philistines are left behind. The truth is there's often no right way—or, at minimum, there are multiple right ways.

In the case of pitching staffs, there's obvious incentive to investigate whether the traditional model is the best or most efficient. Still, there's also obvious incentive to not rush toward the same new strategy that everyone else is—lest you miss out on the market inefficiencies that this class of general manager is supposedly devoted to identifying.

The Diamondbacks' winter, then, is a nifty cut against the grain. You can't suggest they found a market inefficiency, since they paid a hefty (arguably too hefty) price for both Greinke and Miller. Maybe the quips about them living in another world are correct. Or maybe they're just living on another timeline—the one where the Mets won the World Series and the rest of the league decided it needed multiple front-of-the-rotation starters to win a title. No matter where you fall on the spectrum, expect entirely too much to be made how the D'backs perform this season by both sides of the pitching-staff debate.