NEW YORK -- Enough with the narrative, says Edwin Díaz, the Mets’ 25-year-old reliever who can throw over 100 mph, who struck out more than 15.4 batters per nine innings last year and who is one year removed from being considered, without much debate, the best closer in baseball.

“Just because I’ve had one bad season, doesn’t mean I’m a bad pitcher,” Díaz said through an interpreter in late September, “especially when I’ve had three great seasons in Seattle. The fourth one went bad, but you just have to continue working so you can get back to that level.”

It’s not an exaggeration to say Díaz's ability to re-attain those heights could mean the difference between the Mets making and missing the playoffs in 2020. After general manager Brodie Van Wagenen traded for him last December, buying high on a reliever who saved 57 games with a 1.96 ERA for the Mariners in 2018, Diaz finished with only 26 saves and a 5.59 ERA. He allowed as many home runs as in his previous two seasons combined, despite producing the third-best strikeout rate in baseball behind Josh Hader and Matt Barnes (minimum 30 appearances).

Díaz believes his slider, against which opponents hit .297 with a .622 slugging percentage, represents the root of his issues. Unable to replicate his past success with that pitch, Díaz tinkered with his grip late in the year, trying to mimic that of Jacob deGrom. This winter, he plans to throw about seven to 10 bullpen sessions before arriving at Spring Training, compared to the five or six he threw last offseason in Puerto Rico. He’ll spend most of them attempting to refine his breaking ball.

“For sure, the slider’s the most important pitch,” Díaz said. “My goal is to get that back to what it has been in years past. I’ve always said the fastball, anyone can hit the fastball. That’s a pitch about location. But the slider, that’s the main goal just to get that right again so I can be effective.”

While Díaz tries to perfect it, the Mets will have to decide how to deploy him in 2020. The team’s unquestioned closer heading into last season, Díaz ended the season in a timeshare with Seth Lugo, who could see ninth-inning opportunities again next year. But in the Mets’ perfect world, Díaz will give them no choice, reverting to elite form in 2020.

“I do think that Edwin personally took a lot of heat for his performances,” Van Wagenen said. “I know I did as well. But Edwin still saved 26 games for us this year. … It’s far from where we hoped he could be and it’s far from where we believe he will be.”

What Went Right?

When things went well for Díaz, he still looked every bit the unhittable pitcher he was in 2018. Healthy all season, Díaz finished 11th in the Majors with 99 strikeouts and produced one of the league’s best whiff rates. That’s what made Díaz's season so perplexing: at times, he was unhittable.

What Went Wrong?

…and at times, he was not. Díaz’s bugaboo was the home run ball, which bit him in four of his seven blown saves. No full-time MLB reliever posted a higher home run rate than Díaz’s 2.33 per nine innings, while only four lost more games than him and only six blew more saves. In any context, that would be an issue. In the New York fishbowl, it was even more impactful considering the heavy prospect price the Mets paid to acquire Díaz and Robinson Canó, who experienced plenty of issues of his own after the trade.

Best Moment?

Díaz’s most memorable save came on Opening Day, when he buzzed through the Nationals in order on 14 pitches. He continued to enjoy a series of strong outings from there, waking up on the morning of April 29 with eight saves in eight chances and a 0.84 ERA. In retrospect, that was the high point of his season; from then on, Díaz blew seven of his 25 save opportunities, allowing 14 homers in 47 1/3 innings while producing a 6.65 ERA.

2020 Outlook

Van Wagenen went out of his way to state publicly that he won’t trade Díaz this winter, which makes sense: dealing Díaz would mean selling low on a pitcher whose underlying statistics suggest he should be better. New manager Carlos Beltrán must decide if he wants to reinstall Díaz as the Mets’ full-time closer, or have him share the role with Lugo and others. No matter which inning he pitches, Díaz is about to get much more expensive now that he’s arbitration-eligible for the first time. MLB Trade Rumors projects Díaz’s new salary at $7 million, compared to the $607,425 he made last season.