First, we find that the average league leader in reliever IP has dropped well below 100. Over the course of the 1999-2012 span, that figure has frequently descended into the 80s.
But cutting down innings has not resulted in a more consistent year-to-year performance.
And it has not appreciably affected the aggregate drop in high-workload relievers that occurs in the year after.
In the last fourteen years, it appears that managers have deployed extra relievers, cut down the top-level workload by putting more people into more games for less innings per appearance--and they've created a situation where these relievers' decline in innings and effectiveness in the following year is getting more pronounced, not less.
As you peruse the chart, you'll notice another unusual feature. In the early part of the time frame (up until 2005 or so), there were a sizable number of repeaters on the list--Scott Sullivan, Scot Shields, Salomon Torres, Guillermo Mota.
Five years ago, that trend came to a screeching halt. High workload guys are simply not repeating.
The three smaller charts appearing in the text that follows sum up the changes over the 56-year sample.
The first chart, tracking innings pitched in the next year (IPny), shows that the loss for these reliever s is steady at around 80% of the previous year (or, for those of you playing along at home, just over 20%).
The second chart, tracking aggregate ERA+ from previous year, shows that the last fourteen years have suddenly produced a group of high-workload relievers who are markedly lower in the 1999-2012 time frame. The overall figure is just about 20% for the past fifty-six years; for 1999-2012, that decline percentage is up to 27%.
Using relievers in more games and less innings--at least based on the guys at the top of the IP lists--is not producing greater resilience in relievers. And it's not producing better performance in the following year.
[EDIT: You can view Part 1, Part 2, and Part 3 of this series by clicking the links.]
