The Maddening Consistency of Mo

It seems somehow appropriate the the Yankee Empire appears to be crumbling right as Mariano Rivera decides to retire. One of the two players that best exemplified the Yankee Dynasty going as the empire he helped build becomes more and more tenuous. With his announced retirement, the many facets of Rivera's greatness will be lauded and analyzed. The all-time saves leader, the playoff greatness, and--what I consider the most impressive--his annoying consistency.

It is well recognized that relief pitchers can be an extremely variable group, tending to be brilliant for a couple years and disappearing thereafter, like "violent fires [that] soon burn out themselves." This has become so common that it only seems to be a matter of time before this happens even to the best of relievers. Consider this...

• Since 1997, there have 2,250 different relievers to set foot on the mound.
• Of those, 761 have qualified for the Fangraphs reliever leaderboard (45 IP minimum)
• Of those, 209 qualified for the yearly leaderboard in four out of five consecutive years.
• Of those, only 16 pitchers qualified in ten seasons...
• ...And none had more than Rivera's 14 such seasons.

You see where we're going, right? Rivera was always there. Now, it's one thing to be there and be mediocre with flashes of brilliance for an extended period of time (See Alan Embree, Dan Wheeler, or David Weathers). It's an entirely different matter to be consistently brilliant, even with a few bumps in the road.

So let's take a closer look at this consistency, as it first pertains to WAR. To begin with, a sample of 103 relievers who pitched in at least 10 of the 16 seasons was taken. Now, in measuring the volatility of any sample, the standard deviation is often used. In order to take into account that larger values often have more variability--and in the case of WAR, more is better--the relative standard deviation (RSD) is a better measure. This is just the standard deviation of a sample divided by the mean of a sample. So, the more consistent the pitcher is, the lower the RSD is. Here is the top ten RSD(WAR) over the past 16 years.

What about something more traditional than WAR? How does Rivera fare with ERA? Note that here, regular standard deviation was as opposed to RSD.

Prefer FIP to ERA? I'll spare you another table and say that Rivera leads that board too by a solid 0.100 margin, which is a large lead when considering standard deviations and FIP.

Whenever a great retires, it is natural to wonder who will take up the mantle. While it's clear that there will never be a whole package like Rivera, there are relievers who might be able to replicate his consistency. This could be a whole other discussion, but the only other reliever who has been doing this for at least 6 years with any consistency has been Jonathan Papelbon, with RSD(WAR) of 0.353, SD(ERA) of 0.940, and SD(FIP) of 0.682. But again, that's a discussion for another day.

On all these measures that traditionally measure value, Rivera shows up at the top or near the top of the leaderboard. Throwing in the fact that Rivera consistently averaged around 68 IP in non-injured seasons (Yes, he leads in RSD(IP) too if you don't count that injured 2012 season) just adds to the impressiveness. And there hasn't even been a mentioning of the unparalleled playoff numbers.

This is what drove me crazy about Rivera as a non-Yankee fan. Time, age, and injury seemed as helpless against him as all those poor slobs trying to hit his cutter in October. Other relievers, no matter how great, were subject to these nuisances. Eric Gagne went down to injury, Trevor Hoffman got old, and Brad Lidge just fell off the map. But there was an air of inevitability about Rivera. As sure as death and taxes, he would always be there, and always be brilliant.

That's what made his 2012 injury so startling; for the first time it seemed possible that we'd have to conceive of a world where Rivera wasn't there. It's now clear that that world will commence in 2014, and when that time comes, we'll be bidding goodbye to the most consistently great player (Relative to position) in Major League history. As an O's fan, I'm not going to miss Mariano. But that doesn't mean I won't miss the consistent greatness.