The inundation of analytics has changed so much about baseball, from the way it's consumed to the way it's played out. Defensive shifts now occur frequently, hinging almost entirely on the tendencies displayed on advanced spray charts. Stats like Weighted Runs Created Plus (wRC+) and OPS+ have changed the way lineups are structured, trumping long-held stereotypes for what a leadoff man or a cleanup hitter should look like.
And yet bullpen management -- in an era in which the World Series champion Royals have every club focusing on building a dominant relief corps -- remains archaic.
Closers, for the most part, still only pitch in save situations, and most managers continue to assign specific innings to three and sometimes even four of their relief pitchers. They call that "bullpen slotting." It's a deployment strategy disparaged by sabermetrical evangelists ever since Bill James put out his first manifesto on the subject more than 30 years ago, yet there is still no sign of it going away.
The opposing theory is so basic: You want your best reliever pitching in the game's most important juncture, no matter the inning. Why box yourself in with specific roles?
Good luck finding someone within the game who actually believes it can work, however.
"On paper, it actually should and can," said A's general manager David Forst, a Harvard grad who prides himself on outside-the-box thinking.
"These guys don't play on paper, and any manager will tell you that it's one of the most difficult parts of their job. I'm certainly respectful of that. It's something we've talked a lot about over the last few years, in realizing that these guys have routines, they have egos and feelings, and it's important to put them in places where they're comfortable and not just where you think they're most useful. Ideally, you'd like to set up the bullpen where you have your best guys pitching when it matters most."
But there are just so many issues that come with that, all of which can basically be narrowed down to a list of four:
1. What is the most important part of a game?
It seems a lot easier to decipher that in hindsight.
"I don't know how you know what the highest-leverage situation is until the game is over," Giants manager Bruce Bochy said. "You think it's that sixth inning, but it could be the eighth or ninth."
2. Many throughout the industry -- including the most progressive-thinking managers and analytically inclined executives -- still cling to a belief that the ninth inning of a close game carries a heightened level of intensity that can't be duplicated elsewhere.
And because of that, the game's administrators believe those roles should only be filled by the toughest-minded men, guys with the hardened exterior to blow a save, shoulder the blame, forget about it and be unaffected the following day.
Cubs manager Joe Maddon utilizes the theory more than most, using all of his non-closing relievers in versatile, fluctuating roles. But his closer pitches exclusively in save situations because, as he said, "it permits you to work the first eight innings, knowing that he's there."
A key stat seems to support Maddon's usage.
A stat called Leverage Index (LI) helps illustrate the intensity of a situation a pitcher or batter took part in. Last year, each of the top six relievers in gmLI (a pitcher's average Leverage Index when he enters the game) were closers, finishing with no less than 30 saves each.
"Philosophically, I agree with it 100 percent," Mariners GM Jerry Dipoto, a former closer but also one of the first active players to become a SABR member, said of using your best relievers in the highest-leverage situations. "I just think that the way human nature is, you're going to gravitate towards the guy you trust to pitch last. I've never seen a manager that does it another way."
Dipoto's first job in a baseball front office came as a scout for the 2003 Red Sox team that tried a closer by committee -- out of necessity -- and famously failed at it. The strategy hasn't really been utilized since, largely over reason.
3. Egos. Each of the 24 largest reliever contracts, based on average annual value, went to closers.
Non-closing relievers are being compensated much better these days, but save totals remain the most valuable compensation tool. Players know this, and managers live in constant fear that juggling their closers can fracture their clubhouses.
"There's obviously a lot of cache to pitching the ninth inning, and getting saves, and there's a lot of money that comes along with that, too," Forst said. "That is not an inconsequential part of the equation."
The entire baseball landscape would seemingly have to change in order for a practice like this to work.
Pitchers would have to be trained, both mentally and physically, to be ready at any point. Managers must be brave enough to shoulder criticism when late leads are blown using unconventional methods. And relief pitchers must be compensated differently, rewarded for core skills over raw save totals.
But even then, there's an unavoidable element to all of this.
4. Playing it by ear every day would inevitably force relief pitchers to warm up more frequently than they have to, ultimately hindering performance.
At least that's what Angels closer Huston Street believes.
"At the end of the day," Street said, "it's quite simple: There's just not enough energy to go around."
Street has been a closer almost his entire life, from his collegiate days at the University of Texas to the totality of his 11-year Major League career. He estimates that in a given year he actually makes about 100 appearances -- 65 or so when he pitches in a game and then another 30 or 40 from all those times he warms up in the bullpen, sits back down and warms up again. The latter is "every reliever's worst nightmare," Street said, but also an inevitable part of the job.
If a team's best reliever were assigned to the highest-leverage situation, as opposed to merely the ninth inning, Street estimates he would have to warm up, sit down and warm up again twice as frequently, because a lot of time is needed to get ready and because the leverage of a situation can change so quickly.
He believes it would be too much for a bullpen to absorb.
"There is no getting used to that," Street said. "You can't. Your arm gets sore. It just gets sore. That's what happens. "
Street, and basically everybody else polled on the subject, concluded that the theory can work in small sample sizes, like the playoffs, but is unsustainable over the course of a six-month regular season. They ultimately believe the statistical advantages are not enough to outweigh all of the potential hazards that come with it.
"Perfect on paper," Street said. "But in practice, it's the worst idea I've ever heard."
Alden Gonzalez is a reporter for MLB.com. Follow him on Twitter @Alden_Gonzalez and Facebook , and listen to his podcast.
This story was not subject to the approval of Major League Baseball or its clubs.