The unofficial hashtag of the 2017 playoffs is #Bullpenning. Brian Kenny coined the term on MLB Network and in his book on the evolution of baseball analysis, Ahead of the Curve. It’s become a part of his brand over the last year and change, but more recently than that, it’s matriculated into the mainstream, national baseball conversation. This month, with starting pitchers having their days cut shorter than some segments on MLB Now, it’s downright dominating the postseason landscape.

Is #Bullpenning happening? Should it be? Is it good or bad for baseball? Can it be done over a full season, or is this phenomenon confined permanently to this specific window? Are there ways that MLB could stop it from happening, if they so chose? Should they choose to do so?

I love playoff debates, but the number of times these questions have been asked and non-answered is getting excessive. Unwisely, perhaps, I’ve decided that the best way out of these conversations is through them. Let’s do our best to actually answer the important questions in this cluster, so that (going forward) we can talk more about the players and pitches that make up the on-field action of October.

First of all, we need to talk about what #Bullpenning (I’m going to stop using the hashtag now, I promise) really is. Kenny’s concept of it is more or less one of a post-starting rotation baseball world. He believes the evolution of the game is bending toward shorter, more frequent outings for the guys we now treat as traditional starters, and perhaps some longer ones for the hurlers who have lately been locked into hierarchical, one-inning bullpen roles. Never, under the maxims of bullpenning, would a pitcher face the opposing lineup a third time. The idea is to get everyone throwing harder (worrying less about pacing themselves), allow batters fewer chances to get a look at each pitcher’s stuff and sequences, and make decisions according to matchups and situations, instead of doing so under the constraints created by the win and save rules.

Let’s pick that broad definition apart and discuss whether what we’ve seen so far in the Division Series (and the Wild Card games) jibes with it. To me, the top rationale for this strategy has to do with lessening the pain and penalty pitchers suffer as they work deeper and deeper into a given game. There’s legitimate debate about whether the times-through-the-order penalty is a problem of familiarity or of pitcher fatigue, but in either case, bullpenning should avoid allowing that to become an issue. In that regard, 2017 marks a forward leap toward a bullpenning future.

Percentage of Pitches Thrown By Pitchers Facing Opposing Hitter for Third or Fourth Time, Postseason, 2008-2017























Last season saw the real separation from the pack, of course, but that trend has only continued, and become more exaggerated. It’s not just that starters are departing slightly earlier, either. The entire pitching staff is getting involved much more often than they used to. Of the 314 games in playoff history in which at least six pitchers appeared for one team, 34 have come since the start of last October.

That doesn’t mean that we’re in an era of bullpenning, per se. Bullpenning is a strategy. It’s a game plan. Many of the quick hooks and bullpen games we’ve seen so far this month feel more like an emergency scramble than like any kind of tactical attack. Last September, Neil Weinberg wrote an article at FanGraphs about the sudden and sharp turn taken by the longtime trendline toward fewer pitches and innings per start. Weinberg pointed out that, while it might look like the league was taking the protection of their pitchers and the prevention of injuries to starters more seriously than ever, the reality seemed to be that managers were just reacting to outcomes within games, without adjusting for the fact that home runs were flying at record rates.

In other words, what might have constituted cause to remove a pitcher changed from early 2015 to late 2015, but managers didn’t change the performance criteria that prompted pitching changes. That’s where we remain, over a year later. Managers seem to believe (often wrongly) that a pitcher who gives up an early home run (or two, especially) simply doesn’t have it, and that getting that guy out of the game is the only way to keep the opponents from running roughshod over their team. Now, often, lifting the pitcher is the right move, but the thought process that leads to that decision isn’t correct.

Right now, most of the league is falling ass-backward into the proper strategy for winning in October, the way individual teams (like the 2011 Cardinals, 2014 Giants, and 2016 Indians) have in recent seasons. This should not be taken to mean that we aren’t moving toward a bullpenning future. We are. There will still be pitching rotations, but they’ll no longer be five-man or five-day rotations, and the people in them won’t have special status. The future of pitching, barring a change of either rules or the basic logistics of the game, is a whole bunch of guys who pitch between one and three innings every three days or so, with a couple of specialized aces who simply pitch whenever they’re needed most.

None of that will be all that new, really. It’s mostly an old idea, reshaped by newly understood realities. The aces of the first half of the 20th century pitched in relief quite often. The rotation didn’t exist back then; teams sent their best pitchers out there as often as they could. Because there weren’t rigid roles in either the bullpen or the rotation, managers used quick hooks much more liberally. Over time, as pitchers gained a measure of self-determination (through free agency) and the task of pitching in the majors got ever harder, that model went by the wayside, and was replaced by one that guaranteed players various roles.

That shift wasn’t without merit, but as the game has evolved even further, it’s become a suboptimal one. Eventually, we’re going to see teams go back to a plan whereby pitchers throw less in order to throw better and stay healthier, and the pitching change will become proactive again, rather than reactive. It’s just premature to say that it’s happened already.