The New York Mets haven’t assembled as frightening of a bullpen as the New York Yankees have this winter, but at least general manager Brodie Van Wagenen has improved the least productive area of the roster from 2018.
When closer Edwin Diaz was officially acquired from the Seattle Mariners, it wasn’t hard to see just how much of an upgrade this would be. He’s fresh off being the league leader in saves (57), owned the fifth-best ERA (1.96), and produced the second-highest fWAR (3.5) among qualified relievers. The right-hander earned just $570,800 in 2018, but his performance was worth $28.1 million, according to FanGraphs.
As he continues preparing for his age-25 campaign, who knows what the future holds for him in Queens (well, let’s hope it’s mostly good stuff). What I discovered upon falling into a Mets relief pitcher statistics rabbit hole is that his ability to make hitters swing and miss is unmatched when looking at individual seasons since 2000.
The Strikeouts and Swings-And-Misses
Diaz posted career highs in strikeout rate (44.3%) and swing-strike rate (18.9%) in 2018, both of which ranked second in baseball behind Josh Hader (46.7% and 19.0%, respectively). There have been just three Mets relievers to post a strikeout rate even above 30.0% in a single season: Armando Benitez in 2000 (34.9%), Jerry Blevins in 2017 (31.8%), and Billy Wagner in 2006 (31.7%). None of them paired that with a walk rate lower than Diaz’s 6.1%.
This was actually the second time his strikeout rate has surpassed 40.0% in three years. Diaz did struggle a bit in 2017 (compared to his other two seasons) and still generated a 32.0% strikeout rate.
Posting a high swinging-strike rate has also proved to be a pattern during his first three big-league seasons. Since debuting in 2016, that number has settled in at 18.5%, 16.0%, and 18.9%. If he did those in Queens, they’d be the three highest single-season swinging-strike rates by a Mets reliever since 2000. Here are the top five performances:
Where A Lot of The Damage Happens
Diaz boasted an average fastball velocity of 97.3 miles per hour in 2018, which landed him in the top 15 among qualified relievers (Familia landed just inside the top-25 with an average of 96.2 mph). When looking at how this particular pitch performs against opposing hitters, though, it’s not the one that does most of the damage — it’s his slider.
The young right-hander’s four-seamer limited the opposition to a 58 wRC+ while producing a 33.3% strikeout rate and 13.4% swinging-strike rate. But his slider — which he used at a 37.3% clip (a career high) — produced an eye-popping 21 wRC+, 56.4% strikeout rate, and 28.4% swinging-strike rate.
And, just for fun, here’s the three-year progression of those stats when looking specifically at Diaz’s slider:
Saying this is a filthy pitch is probably quite an understatement.
Looking Forward to 2019
It wouldn’t be fair to expect Diaz to duplicate what he just did for the Mariners. Although he has shown an ability to sustain some of his peripherals in more than just a single season, waiting for another 3.5-fWAR campaign isn’t realistic. After all, his most recent performance is a full win higher than the best Mets relief pitcher season since 2000 (Addison Reed, 2.5 in 2016).
Even when accounting for regression — which a number of projection models are predicting — he’d still immediately jump to the top of franchise leaderboards for the time period we’ve been discussing. FanGraphs’ Steamer Projections currently have him pegged to post a 2.45 ERA with a 37.2% strikeout rate, 8.4% walk rate, and being worth 1.4 fWAR in 65 innings.
We all knew that acquiring Diaz will provide manager Mickey Callaway with one of the game’s elite closers, but his specific ability to make hitters swing and miss is something that’s rarely been seen coming out of the Mets’ bullpen.