Why did major league teams evolve to designate their best relief pitcher as the closer, who enters the game only in save situations? It began in the 1950s, when relief pitchers started to pitch more innings than starting pitchers: [iframe src="http://cf.datawrapper.de/k6txC/3/" width="710" height="400" frameborder="0" allowfullscreen="allowfullscreen"]
Teams carried fewer relief pitchers before the 1980s. Generally, they had just one or two "firemen", who are ace relief pitchers, and a few mop up guys for low-leverage situations. They almost always entered the game before the 9th inning with men on base. Bruce Sutter was the first relief pitcher to start more than 20% of his career games in the 9th inning. John Franco was the first pitcher to hit 50% in 1987, and Lee Smith broke 75% in 1994. As far as baseball history goes, the modern closer is a very new thing.
Up until the late 1960s, relief pitchers posted worse ERAs than starting pitchers. But that changed as, and relief pitchers now post lower ERAs than starting pitchers:
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Why are ERAs lower? As far as I can tell, there are three reasons:
- Better pitching. Pitchers who operate in shorter stints and don't see batters more than once can pitcher better.
- Specialization. Pitchers who are good against right-handed batters see more right-handed batters, and pitchers who are good against left-handed batters see more left-handed batters. This increased as bullpens grew larger.
- Inherited runners. If a pitcher is having a bad day, or about to face a batter he doesn't tend to perform well against, the team can sub in another pitcher who will do better.
The first two get a lot of attention, but I think #3 is the most important, and explains how the closer position naturally evolved. It makes sense to generally deploy your relief pitchers from worst to best. You want to have Dellin Betances available to clean up Adam Warren's mess, just in case.
It also makes sense to generally plan out which innings to put a player out there. Teams want to use as few relief pitchers as possible in order to win a close game. If your starter goes 7 innings, you want Dellin Betances, Andrew Miller, Adam Warren to pitch much more often than Esmil Rodgers and Justin Wilson.
So, in a close game your closer becomes the last guy who deploy out of your bullpen. He can't be too specialized, because there is no one left to take the ball from him.
You'll almost always hear the same line about closing. Here is Tony La Russa:
"Sure, games can get away from you in the seventh and eighth, but those last three outs in the ninth are the toughest. You want the guy who can handle that pressure. That, to me, is most important."
Boy, do I hate that line. A close baseball game is overloaded with pressure situations. A tied, 6th inning game with one out and two runners on is a pretty high pressure situation. We have statistics like WPA to quantify this.
I'm willing to bet a whole lot of money that the 'pressure' explanation for 9th inning closers was created retroactively, after the role had naturally evolved from a fireman to the more ordered bullpen roll-out. That in turn led to the 9th inning becoming some kind of mystical prestige thing, and relief salaries became tied to saves. By accident, we all of the sudden have this thing called the 'closer', who pitches the 9th inning in save situations almost exclusively.
It is plainly evident that this is not the best way to run a baseball team. It makes much more sense to reserve your best relief pitcher for the most important outs in the game. A dominant pitcher like Dellin Betances should almost always come in with men on base. Betances only has so many bullets to shoot each season, and it is stupid to waste them on low-leverage situations. This argument has been made a thousand times, so I don't need to repeat it again.
It is bizarre that the only real barrier to teams maximizing their ability to win games with relief pitching is some combination of psychological and monetary incentives. I'm sure Betances badly wants to close games next year. Doing so would set him up for a huge payday in arbitration, where closers are rewarded huge salaries. Setup men, without the saves, are awarded much lower salaries. I'm sure there are also corresponding prestige and personal incentives for earning saves too.