While Robinson Cano has the bigger name recognition of the two newest Mets, the true centerpiece of the deal with the Mariners—the reason why the Mets parted with outfield phenom Jarred Kelenic—is Edwin Diaz. Arguably the best closer in the game, the 24-year-old saved 57 games for the Mariners last season, posting a 1.96 ERA, 0.79 WHIP, and 1.61 FIP over 73 1⁄3 innings of work. His 44.3% strikeout rate was second in the majors last season and the third-best mark in American League history. His 38.2% K-BB% was the best in baseball. His save total ranks second all time in a single season and is a Mariners franchise record.
Despite having a similar Pythagorean win% to the Mets last season based on runs scored vs. runs allowed, the Mariners won 89 games in 2018, while the Mets won 77. Diaz was a big part of that. The Mariners were 66-0 last season when Diaz entered a game with the lead and 61-0 in his save opportunities. The Mariners played in a huge number of one-run games and went 36-21 in those contests. In one-run games, Diaz’s ERA was 0.88. He was named the 2018 Mariano Rivera American League Reliever of the Year.
While last season was historically good for the young righty, he has already built himself quite the career in three major league seasons. He holds a career 2.64 ERA and has converted 90% of his save opportunities. He has already struck out 300 batters and saved 100 games. Since saves became an official stat in 1969, he is the second-youngest pitcher to reach 100 saves. He was also only the second pitcher in history to notch at least 50 saves and 100 strikeouts in a single season.
Diaz burst onto the scene quickly and was considered an elite pitching prospect at the age of 22 while starting games in Double-A in the Mariners system in 2016, after being drafted in the third round in 2012. He was already showing two plus pitches with high strikeout totals and an impressive amount of control. Unlike the career arc of most starting pitchers turned relievers, Diaz was still considered to have mid-rotation potential when the Mariners took a risk by converting him into a reliever while still in the minor leagues. The risk paid off in a big way. Diaz was in the majors just a few short weeks later, skipping Triple-A entirely and hit the ground running from there. His fastball velocity jumped from shorter stints on the mound and his slider went from a plus pitch to a plus-plus pitch.
He was fifth in Rookie of the Year voting in 2016, but saw some regression in 2017, as hitters started making better contact with his pitches. He also posted an above league average home run per fly ball rate in his first two seasons. But in 2018, he bounced back in a big way, lowering that home run per fly ball rate substantially and generating more swings and misses on pitches outside the strike zone. He threw his slider about 10% more often in 2018, but his major adjustment between 2017 and 2018 seemed to be his fastball sequencing. He switched from a two-seam fastball to throwing primarily a four-seam fastball with the two-seamer serving as his secondary fastball. As a result, the wOBA off his two-seamer dropped from .323 in 2017 to .219 in 2018 and the whiff rate on the pitch went from 13.5% up to 20%. An astute analysis from Beyond the Box Score postulated that his increased effectiveness on all of his pitches may have been due—at least in part—to a change in release point from 2017 to 2018, allowing him to command them better and get sharper break. The result looked a little something like this.
Edwin Díaz, 97mph Fastball and 91mph Slider, Overlay with Tails. pic.twitter.com/wDtx28C2ZW— Rob Friedman (@PitchingNinja) September 16, 2018
This is encouraging and tells us that last year’s results are no fluke. Diaz made the adjustments he needed after the 2017 season to go back to being dominant. The Mets are banking on him staying dominant for many years to come. 2020 will be Diaz’s first year of arbitration eligibility and there is no doubt his price tag will be steep if he continues performing at the level that he did last season. Nonetheless, he is still likely a cheaper option than any high-end reliever available on the market and is a better pitcher than any of them at this stage in his career to boot.
While concerns about Diaz’s durability, given his somewhat violent mechanics and the fact that a bone spur in his right elbow dropped his signing bonus when he was drafted, may have played a role in his conversion from a starter to a reliever, the bone spur has yet to be an issue for Diaz. He has never been placed on the disabled list in the major leagues. There is a chance this may become a problem for him in the future, but pitchers deal with spurs somewhat routinely. Noah Syndergaard has a bone spur that has not required surgery, while Steven Matz had to have a bone spur surgically removed at the end of the 2016 season. A bone spur that is painful enough to prematurely ends a pitcher’s season is “uncommon,” according to medical experts.
Oh, and one final detail: if you are still mourning the loss of Danza Kuduro (and let’s be honest, who isn’t?), rest assured that Edwin Diaz’s walkup music is extremely good. I know I’m excited for the first time this is blaring at Citi Field heading into the ninth.