If you spend any time following the financial markets, you're likely familiar with the term "bubble." In not a nice way. An apparently new way to become well-to-do becomes popular. More people (who don't necessarily know the entire backstory) enter the field. They're all making money. Until, suddenly, they're no longer well off. The bubble popped.
Regardless how far you go back with baseball, bullpens were handled differently then. I claim the early-1970s as my kindergarten, with 1969 being my preschool. Starting pitchers were expected to pitch until they were pinch-hit for late In the game. Complete games were a regularity. Eventually, executives decided that it was possible to locate pitchers able to throw hard for an inning or two, and bullpens began to lengthen. Two lefty specialists became the norm, and games began to slow down. Eight man bullpens and four hitter benches became the trend.
The bubble kept bubbling. “Our closer ought to pitch the home ninth in a tie game, to extend proceedings.” A hiccup with avant-garde bullpen usage types is that they rarely account for a few things I consider very basic. How many games should any pitcher throw in over the course of two weeks? Does "getting hot" (being ready to relieve, even if not needed) change the math? How many innings or pitches should a reliever be responsible for in a two-week period? They want outs, and wins. I would prioritize health and effectiveness.
If a reliever gets overused, he becomes useless for a day or more. If he's used when cooked, he's of no value. Sometimes, overuse leads to injuries, including Tommy John surgery. There are no take backs once the damage is done. A team with four leverage relievers is very vulnerable when two are out for extended periods, and the third suddenly can't record outs. Adding veterans in the off-season sounds good, until they under-perform, as well. League rules are set up so it's relatively difficult to have twelve quality veteran relievers to shuttle through the system every year.
A handful of years ago, starters were going six or so innings per start. A team had to account for about 20 bullpen innings per week. A decent leverage veteran could toss in the range of 70 innings per year, or two to three per week. Give him the ninth for the save, and split the other 17 over six to nine other guys.
Now, teams are all about grinding at-bats. Even if the strikeouts are plentiful, get to the bullpen by the fifth or sixth inning. Now, 20 innings per week becomes 25 or 30. That many quality relievers don't exist. Guys entirely competent at two innings per week are being used four or five times a week for something they never really bargained for. Watch a team over the course of two or three weeks, they might have four or five bullpen blowups. Getting MLB hitters out is hard. It's more difficult with your C-game.
How can teams get to a point where they can survive the onslaught of increased weekly innings over a six month season? One common refrain is to bring back the long reliever. I remember the long reliever. He was usually a veteran with a bad arm, that the team kept around as a fire extinguisher. The starter got pounded, and lifted in the third. The 33-year-old soon-to-be pitching coach tossed into the eighth, and gave up five runs.
Teams don't do that, anymore. They bring in 96, followed by 95, then some 89 (the lefty), and a call-up pitches the last two, before being sent back. What really shreds the bullpen now is close games. Leverage relievers are like the four year college starter. A youngster with a 5.85 ERA won't get the leverage spot. The four guys that are trusted get summoned regularly. And their performance sometimes lags commensurately.
Two groups are to be worried about regarding the bullpen bubble. One is the team. The teams that find a way to have 14-20 usable relievers in a season will endure just fine. They will be defined by locating talent, staying in front of injuries, and having enough spare pieces in the pipeline to add what's needed without surrendering too much developing talent. About five will be really good at this, and about five will be terrible at it. The rest will form the middle. Another group is less able to deal with bullpen implosions? Many fans. Unaware that bullpens all have difficulties, and unsure why, they rage when a professional hitter on the other team does his job. Perspective is an often-ignored value in following a team.
The Cubs recently signed Craig Kimbrel. This will help the back end of the bullpen the next few years. However, he won't be a panacea. He might not be as good as before, and the weak outings will be magnified. Upgrading two or three innings per week should shove the other leverage guys back into the middle of the game.
If the offense does enough, and the starting pitchers go long enough, the team should do well enough. The bullpen bubble has blown up across the league due to overuse. Bullpens have been a problem for contenders back to the 1970s. Complaining about bullpen depth isn't new. What would be is coming up with long-term fixes for the bullpen bubble problem. What’s your solution?