Top 10 relief pitchers in MLB

Wade Davis and Aroldis Chapman have both posted remarkable numbers the past two seasons. Getty Images

The collective work of relief pitchers is more important than at any point in baseball history, with an increasing number of teams -- especially ones with midlevel or lesser budgets -- relying more and more on deep bullpens and less on starting pitchers. The Kansas City Royals, of course, have become the working model of this, winning the World Series in a year in which their starting pitchers ranked 24th among 30 teams in innings. The team excelled largely because of a deep and versatile bullpen.

But at the same time, the perceived value of each individual bullpen piece seems to be diminished, as teams account for the volatility of reliever performance and the relatively short span of high-end excellence. By the time the winter is over, the highest-paid free-agent reliever, which is probably Darren O'Day, will get something in the range of $30-35 million -- more than a dozen starting pitchers will exceed that. The biggest contracts doled out to free-agent relievers in recent years are the $52 million contract signed by Jonathan Papelbon and David Robertson's $46 million deal, and both agreements are generally regarded within the industry as major mistakes.

This is probably because a lot of teams view relief pitchers in the way that NFL teams look at running backs: There are plenty of similar options. Pitchers train to throw high-end velocity in this era in a way they never have before, and almost every bullpen seems to have at least a few guys who throw in the mid-90s or faster.

According to FanGraphs, there were 93 relievers who posted an average fastball velocity of 92 mph or higher last season.

Veteran hitters will tell you that hitting has never been more difficult because of the parade of relievers they face after the fifth inning, with their triple-digit fastballs and cutters and sliders and splitters.

Today, as part of our ongoing positional rankings -- I ranked the top 10 starting pitchers Monday -- here are the top 10 relievers in the majors, based on the observations of rival evaluators and players:

1. Wade Davis, Kansas City Royals

Wade DavisOver the past two seasons, Davis has pitched 164 1/3 innings, and in those, he has allowed 23 extra-base hits. Think about that: That's one extra-base hit every seven innings or so. Among the 623 batters he faced in 2014 and 2015 (regular season and postseason combined), he allowed three homers. Three.

Hitters will tell you that Davis' stuff and command is so good that it seems as if they have nothing to swing at, and their chances of doing any serious damage is infinitesimal. The results reflect that.