This Yankees 'pen might be best ever ... by far

The Yankees bullpen looks like it could be historically great. Again.
This time last winter, we were saying the exact same thing. We predicted that the 2018 Yankees could have the best bullpen ever… and they went on to post the highest Wins Above Replacement total of any relief corps in Major League history. That was following a similarly dominant season the year before -- the 2017 Yankees are third on the list.
The 2019 Yankees might be even better.
As of Thursday, when they reportedly agreed to a three-year deal with free agent Adam Ottavino, the Bronx Bombers' bullpen looks something like this: Aroldis Chapman, Zach Britton, Dellin Betances, Ottavino, Chad Green, Jonathan Holder, plus one or two of Tommy Kahnle, Jonathan Loáisiga, Stephen Tarpley and Domingo Germán.

That group currently projects at 6.2 WAR, going by FanGraphs' preseason Depth Chart projections. That's the top total projection for any team by a wide margin -- the Brewers are second at 4.7 WAR, followed by the Mets at 4.2 WAR. 
2019 projections for Yankees RP
Via FanGraphs' Depth Charts
LHP Aroldis Chapman: 2.0 WAR (65 IP, 2.76 ERA, 13.4 K/9)
RHP Dellin Betances: 1.5 WAR (75 IP, 2.84 ERA, 13.4 K/9)
LHP Zach Britton: 0.9 WAR (60 IP, 3.14 ERA, 8.6 K/9)
RHP Adam Ottavino: 0.8 WAR (65 IP, 3.85 ERA, 11.3 K/9)
RHP Chad Green: 0.8 WAR (70 IP, 3.32 ERA, 11.3 K/9)
RHP Jonathan Holder: 0.1 WAR (60 IP, 4.32 ERA, 8.8 K/9)
RHP Tommy Kahnle: 0.1 WAR (50 IP, 3.93 ERA, 10.3 K/9)
If they hit those projections exactly, the 2019 Yankees would come in behind the 2017 team's 9.4 WAR and the '18 team's 9.7 WAR. But projections are conservative -- and it's not hard to see the '19 Yankees exceeding theirs.
Here are five ways the 2019 edition of the Yankees bullpen could top even the last two years.
1. Ottavino outpitching David Robertson
Ottavino essentially fills the role left by the departing Robertson, who signed with the Phillies. And while Robertson gets better 2019 projections (1.4 WAR to Ottavino's 0.8), likely due to his more consistent track record, Ottavino's '18 numbers were better across the board.
Robertson in 2018: 1.5 WAR
3.23 ERA, 2.97 FIP, 11.76 K/9, 32.2% strikeout rate
Ottavino in 2018: 2.0 WAR
2.43 ERA, 2.74 FIP, 12.98 K/9, 36.3% strikeout rate
And there's good reason to believe in his breakout, as MLB.com's Mike Petriello detailed in October. Among the 91 relievers to face 250 batters in 2018, Ottavino allowed the fourth-lowest expected wOBA -- that's Statcast™'s overall quality-of-contact metric. Robertson ranked tied for 29th.
Lowest xwOBA allowed, RP, 2018
Min. 250 PA

1. Edwin Díaz: .211
   
2. Josh Hader: .229
   
3. Blake Treinen: .230
   4. Adam Ottavino: .231
   
4. Dellin Betances: .237
   David Robertson: .276 (T-29th)
   2. A full season of a dominant Britton
   Ottavino was the Yankees' second key free-agent relief signing this offseason. Bringing back Britton was the first.
   New York only got two months and 0.1 WAR of Britton in 2018 after trading for him in late July, and he was just getting back to form from the right Achilles surgery that kept him out until mid-June. Now the Yankees have him for a whole year, and if he's at his best they'll get closer-type production out of a setup man. In his dominant 2015 and '16 seasons with the Orioles, Britton exceeded 2 WAR both times.
   The left-hander's heavy sinker, which he throws over 90 percent of the time, makes him perfectly suited to keep balls in the yard at Yankee Stadium. After he regained his velocity in July, Britton generated an 80 percent ground-ball rate with his sinker. Almost all hard contact against him stays on the ground.
   Highest GB rate on 2-seamers/sinkers, 2018
   July through end of season
   
5. Adam Cimber: 89.1 percent
   2. Zach Britton: 80.0 percent
   
6. Joe Musgrove: 78.8 percent
   
7. Brad Ziegler: 78.0 percent
   
8. Jonny Venters: 73.6 percent
   3. Chapman retaking the MLB closer throne
   Maybe the most feared closer in the game when he's at his peak, Chapman has been hampered by shoulder and knee issues over the last two seasons. He only ranked 10th among relievers with 1.9 WAR in 2018, but he could easily jump into the 3 WAR range that Treinen, Diaz and Hader occupied last year. Chapman averaged 2.7 WAR from 2014-16, and his unique triple-digit heat from the left side puts that level of season well within the realm of possibility.
   Most 100+ mph pitches since 2016
   2016: Chapman's 1st season with Yankees
   1. Aroldis Chapman: 1,078
   
9. Jordan Hicks: 659
   
10. Mauricio Cabrera: 342
    
11. Joe Kelly: 219
    
12. Noah Syndergaard: 206
    And really, in addition to Chapman, Betances also has that type of elite-season potential. His 1.8 WAR in 2018 was just behind Chapman's, but the big right-hander has also been in the 3 WAR range in the past -- setting up Chapman from 2014-16, he averaged 2.8 WAR. It's just a matter of command. Betances is often erratic, but when he locates, his fastball-breaking ball combination is near-unhittable. There's a reason he's the only reliever in MLB history with five straight 100-strikeout seasons.
    4. Holder's continued emergence
    One of the hallmarks of the great Yankees bullpens of the last couple of seasons is how they've had lesser-known names emerge as reliable relievers. In 2017, Green converted from a starter to a reliever and became one of New York's most lights-out bullpen arms. In '18, Holder had a breakout of his own after developing a slider as a weapon to use against right-handed hitters and a changeup to use against lefties.
    Those are real changes, signs Holder could be valuable again in 2019. But the 25-year-old right-hander, who gave the Yankees 1.3 WAR in 2018 after pitching 66 innings with a 3.14 ERA in 2018, is projected for just 0.1 WAR this season. If he builds on last season, he'll top that.
    5. One breakout or bounceback
    Think about how valuable Kahnle was for the Yankees in 2017 after coming over with Robertson from the White Sox. He dropped off the map almost completely in '18 after dealing with shoulder issues, diminished velocity and a loss of control. But he's still just 29, and if he has any sort of bounceback in 2019, that's an additional source of bullpen production the Yankees aren't necessarily counting on.
    And what if the next Green or Holder is waiting in the system? Maybe it's someone like Loaisiga, who's ranked New York's No. 2 prospect and the No. 66 prospect in baseball by MLB Pipeline. If the 24-year-old right-hander can't crack a crowded Yankees starting rotation in 2019, it's easy to envision a scenario where he ends up a useful contributor out of the bullpen. The potential is certainly there.