This is the third year I've done a series reviewing players by position. I could be mistaken, but I don't believe I've ever evaluated relievers before, mainly because my old methodology had so many dots that it became downright confusing. What a reliever is continues to change and evolve, from the old days when he was just a rubber-armed mediocre pitcher who entered the game when the starter got lit up to today's hyper-specialized roles. It's a very real possibility that I should break up relievers into setup men and closers--or I can be like Cubs manager Joe Maddon and make those roles extremely malleable.

The basis for this post is a Tableau data visualization that plots a player's FanGraphs Dollar Value (FG$V) on the horizontal axis and his pro-rated 2015 salary on the vertical. In 2015, one point of fWAR is worth around $8 million, so the horizontal axis also shows which relievers have the highest fWAR. Scrolling over data points shows a wealth of information, and players with red dots are free agents after this season.

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I wrote about Dellin Betances of the Yankees some time back, mostly out of a mixture of awe and curiosity to see if he could maintain his performance. The main point of that post was that he had more strikeouts than baserunners allowed, something that's really hard to do. Guess what--he's still doing it. Through Friday, he had 83 strikeouts versus 40 baserunners (21 hits, 21 walks, and 2 home runs, which I subtracted from hits). Only 8 of his 24 inherited runners have scored, which implies he's being used in high leverage situations and not just entering at the top of an inning and overwhelming the opposing hitters.

This is a screen grab from the mlb.com Statcast page on the pitches with the highest velocity this year--see if you can notice a subtle trend:

At least through Friday, this page lists one pitcher only, flamethrower Aroldis Chapman, hopelessly toiling away for a Reds team already planning the offseason golf outing. I don't rule out by the time this post runs he could be wearing a different uniform, and I won't allow myself to envision thoughts of him with the Cubs (especially after the way their game on Friday ended, and don't get me started on Saturday), but if the Cubs are going to continue to lead the league in one-run games, they could use someone like him. Or preferably someone not like Rafael Soriano.

What do you do if you're the White Sox, a team built to win right now but is floundering and going nowhere, built on a heap of overpriced and underperforming veterans and younger players who aren't stepping up as hoped? Do you trade David Robertson, a closer on a team which really doesn't need one, or do you hang on to him and hope the next three years to which he's signed are better for the Sox? It's a very good question, because chances are he won't return all that much in trade value, certainly not anything that will be of immediate help. It's the conundrum all teams have when they're effectively out of contention and viewed as the cadavers of MLB, ripe for the harvesting. My gut tells me Robertson will be a White Sox come August 1st, not because he isn't being actively shopped, but because GM Rick Hahn won't be impressed with what is offered. I would tend to agree.

Remember that ridiculous season Koji Uehara had in 2013 with a WHIP of 0.565? Here's how that season ranked among relievers (min 30 games--see the full list here):

Hey, that's pretty good! Note the age--using solid math skills that are a prerequisite for writing for BtBS, he's two years older now and still putting up a WHIP well below one. He's doing it for the going-nowhere Red Sox, so this is becoming a trend I'll have to buck sometime soon.

I've always had an unnatural love for Glen Perkins that I really can't explain. The fact he's a Twin shocks me, since he had trade value the past two trade seasons, but I suspect like the White Sox, they were underwhelmed with what was offered. I'll freely admit I'm shocked at how the Twins are performing, and I'll give one brief reason why--this chart plots team winning percent versus their cumulative fWAR, both pitching and fielding:

You can see the data throughout baseball history (click on the FG WAR tab), and generally speaking, teams with the better cumulative team fWAR are the playoff teams, which makes logical sense because they have the better players. The Twins are the outlier this year, but in an American League that has one dominant team, the playoff picture is up for grabs. Unfortunately for the Twins, that one dominant team resides in their division.

Speaking of that team, how is the late-inning threesome of Kelvin Herrera, Wade Davis, and Greg Holland doing for the Royals this year? Pretty good, but not as lights-out as last year. Click the team tab in the data viz and select Royals to see for yourself--both Holland and Herrera are having good years, nothing spectacular, but Wade Davis is continuing to be as dominant as he was last year. Davis is under team control through 2017, whereas Holland enters free agency after 2016--it will be interesting to see if the Royals let him walk and install Davis as their closer, but one year is an eternity for relievers.

More so than the other positions, use the data filters in the data viz to winnow the amount of data shown, because it really is overwhelming. Relief pitching will only grow in importance, and this chart shows why:

I was listening to Cubs TV play-by-play man Len Kasper talk on Chicago sports talk station 670 The Score and state that teams need to score their runs early because they're tougher to come by later in the game. This chart shows when the closer began to be used, and the gap between runs scored in later innings is continuing to grow. As teams replaced starters on their third or fourth time through the order with a fresh arm throwing 95+ mph heat, those words have never been truer.

Unfortunately, consistent bullpen help is also one of the trickiest pieces to find. Outstanding performance in one year doesn't necessarily translate into the next, which is why big money isn't really spent on relievers any more. Mariano Rivera was a one-of-a-kind player who briefly skewed baseball thinking ("I got it--we need a stud reliever like Mariano, so let's pay big bucks like the Yankees did! What can go wrong?"), and chances are Jonathan Papelbon is the last of the big bucks reliever for some time, or at least until Craig Kimbrel or Aroldis Chapman reach free agency. This doesn't make relievers any less important--when the prevailing attitude is six innings and turn it over to the pen, teams better have a solid bullpen.

Scott Lindholm lives in Davenport, IA. Follow him on Twitter @ScottLindholm.

