Leap to Elite: Edwin Diaz Can Be The No. 1 RP in 2021

Edwin Diaz is currently the seventh relief pitcher off the board in fantasy, and fourth closer if you remove SPRPs from the equation. That hardly qualifies him as being underrated in any major way, but his ADP of No. 85 overall doesn’t indicated the potential he really has to be absolutely elite at the position.

For context, Diaz is going nearly 30 picks later than Josh Hader of the Brewers and Liam Hendriks of the White Sox, and almost a full round later than Yankees closer Aroldis Chapman. It’s worth noting that one of the reasons former Mets GM Brodie Van Wagenen has “former” as a qualifier was his decision to trade a top prospect to Seattle for Diaz, who rewarded him with a 5.59 ERA in 2019. That came as Diaz was widely drafted as the No. 1 closer, and that kind of third degree burn can tarnish a dude’s reputation with fantasy owners forever. We can’t overlook the bad luck Diaz had in 2019 though; His xFIP sat at 3.07, more than two full runs below his ERA, and his HR/9 spiked to 2.33. That’s an absurd number, and way above his previous career-worst mark of 1.36. Diaz has three other seasons in which he’s comfortably below one home run per nine.

Diaz is an elite source of strikeouts. In his rebound campaign in 2020, he posted a career-best 17.53 K/9, and he hasn’t been below a 15 K/9 in three seasons, even when he bombed in 2019. That K/9 is higher than Hader’s (14.68), Hendriks’ (13,14) and even Chapman’s (16.18).

He finished the shortened 2020 season with a 1.75 ERA that was in line with his 2.18 FIP and 2.29 xFIP, and did all that despite a very dangerous .381 BABIP. In fact, when he melted down in 2019, his BABIP was at .377; with a BABIP that high over the course of nearly a season and a half, he’s due for a wild regression to the mean. With his strikeout ability, he has the potential for a microscopic ERA if he can lower that BABIP back to the level it was during his final two seasons with the Mariners when he broke out. And there’s no doubt he should benefit from the improved infield defense that should be present with Francisco Lindor and Jeff McNeil up the middle.

The biggest issue facing Diaz is walks. He issued free passes to a career-worst 4.91 per nine in 2020, bailing himself out by stranding nearly 90% of baserunners. That kind of strand rate is not what you want your top RP to rely on, even with wicked strikeout stuff like Diaz possesses. But it’s not like Diaz is alone in this regard. Hader walked 4.74 per nine in 2020, and posted a 3.79 ERA with a FIP and xFIP over 4.00 and he’s still the consensus top closer. Chapman has flirted for years with walk rates in the high 3s per nine, and Hendriks has much better control, but isn’t on the same level with his strikeouts.

Getting further under the hood, Diaz only gave up hard contact a quarter of the time in 2020, down from nearly half the time in 2019, and posted a 43.2% ground ball rate which isn’t far off from his peak number (46/4% in 2017). The improvement seems to correlate with his increased slider usage  -- which was down 3% in 2019 – which had a value of nearly four runs. Diaz’s swinging strike rate rose to 21.5%, the highest of his career, in 2020. He has increased the velocity of his fastball to 98.3 mph, simultaneously dropping his slider velocity to 94.5 mph (from 96.4). That seems slight, but appears to have dramatically increased his effectiveness.

Lastly, we’re talking about a closer here, and the most important stat is saves. The Mets have a new owner, and he’s made an impact immediately, bringing in Lindor, C James McCann, and SP Carlos Carrasco as major additions. He has also made lesser additions to improve the total roster such as utility man Jonathan Villar, RP Trevor May and OF Albert Almora Jr. Most projection systems have the Mets comfortably taking the NL East crown, and more victories should equal more save opportunities. He has a secure position atop this bullpen, and one of the best surrounding rosters in MLB. Diaz will be near the top of the position in save opportunities and strikeouts, and he’s due insane positive regression on his BABIP. He’s likely the best bang for your buck at RP entering 2021, and he’s definitely a player worth reaching for.