Who is Edwin Diaz?
First things first. Edwin Diaz is an amazing baseball player. He seems like an even more amazing teammate but we're going to focus on him as a baseball player for Fanpost #2. I'll be honest I don't make it to many games these days but I was spoiled this year. I was 3-0 in getting to see Edwin Diaz games in person and he did not disappoint. The Mariners without Edwin Diaz is a sad thought but since I called for his trade I thought it would be a good idea to dive into why.
First some fun stats:
1) Edwin Diaz had a 3.5 win season last year. As a reliever this is a top 5 season since 2000 with the likes of Kimbrel, Gagne, Chapman, and Kenley. More on them below.
2) Diaz has 2 seasons now over 15 K/9 and under 3 K/9. Kimbrel and Aroldis are the only two other players to accomplish this. We're starting to see a trend here.
3) Diaz's 6.4 WAR through his age 24 season is bested only by Kimbrel (7.0 WAR). Ding, ding, ding we have a comp.
So now that we've figured out that we've seen Edwin Diaz before and his name is Craig Kimbrel it's time to dive into what we can reasonably expect Edwin Diaz to look like in the future. I decided to look at all relievers who have posted a 3+ win season with a K/9 well north of 10 and had a 3+ year run of dominance. The only player this really tosses out of the equation is Mariano Rivera which is fair because no one is Mariano Rivera. Here is the list in no particular order:
Craig Kimbrel
Aroldis Chapman
Kenley Jansen
Dellin Betances
Andrew Miller
Eric Gagne
Brad Lidge
Francisco Rodriguez
Billy Wagner
Jonathan Papelbon
Joe Nathan
Greg Holland
Kimbrel, Chapman, and Kenley all just wrapped up their age 30 seasons and entered the league during their age 22 season. That seems oddly specific but for today's exercise this is actually extremely helpful. Diaz also entered the league during his age 22 season and blew the doors off the league. Here's what to expect from Diaz based on the success of Kimbrel, Chapman, and Kenley in their age 25-30 seasons:
Kimbrel - 12.1 WAR, 372.1 IP, 2.3 WAR/70 IP, peak of 3.3 WAR in 2017
Chapman - 13.2 WAR, 343.2 IP, 2.7 WAR/70 IP, peak of 2.8 WAR in 2014
Kenley - 13.4 WAR, 403 IP, 2.3 WAR/70 IP, peak of 3.6 WAR in 2017
All three remain elite relievers through their age 30 season and we should expect similarly from Diaz. For perspective 2.3 WAR would have ranked 5th in the MLB for relievers last year. Diaz has probably peaked year 3 with 3.5 WAR but there are good odds that another 3 win season is in the cards.
Longer term outlook:
If you're inclined to look at things more long term then Wagner, KRod, Papelbon, and Nathan are your comps. All four threw at least 496.2 IP after their third relief season.
Wagner & Nathan averaged 1.8 WAR per 70 IP
Papelbon averaged 1.5 WAR per 70 IP
KRod averaged 0.9 WAR per 70 IP
Billy Wagner is the comp here with the ability to go above 15 K/9 in his career.
So why trade Diaz if there is a reasonable expectation that he'll be an elite reliever for the near future? Even with Diaz the Mariners bullpen was the 7th best in baseball. They had one other everyday reliever over 10 K/9 and he's a free agent in 2020. An elite closer is a great asset to have if you're in the playoffs but the Mariners are unfortunately trending in the wrong direction. The return on closers established by the Aroldis and Kimbrel trades can be substantial and Diaz's combination of pedigree, age, and club control should net a very large return. If the Mariners are interested in tearing it down to the studs (or leaving some drywall) they should at least consider finding out what the return for Diaz could be. Then all they need to do is find the next AA starter to convert into the next Diaz. Just don't ask me who that should be.