The 24-year-old collected his league-best 50th save of the season in the Mariners' 4-3, 10-inning win over the Arizona Diamondbacks, meaning Seattle manager Scott Servais had to follow through on a bet and get a haircut like that of his closer.
While Diaz usually keeps the ball after each of his saves, he gave Saturday's to Servais in honor of the bet.
"We had a little bit of fun with it today," Servais said of Tuesday's payoff. "I had no idea how white my scalp is and the gray is just that's it."
Diaz supervised Servais' shearing while wearing an "Electric Eddie's Barbershop" cap that was gifted to him by the manager.
"I think he looks good," Diaz said. "He looks like the best swaggered manager in the league right now."
The finished product. 💇♂️— Seattle Mariners (@Mariners) August 28, 2018
This photo belongs in a museum. pic.twitter.com/LYVoxUJqjl
While Diaz approves of Servais' new do, the 51-year-old manager said he is done with making wagers for a while.
"I made the comment as [Kyle] Seager as he is looking at me and laughing at me, 'I said Kyle, if you go for two homers and 4-for-4 tonight, I will go with the Seager tomorrow,'" Servais said of his third baseman, who keeps his hair buzzed. "But I quickly stopped that because it may happen. I'm not doing it. No more stupid bets."
Diaz had his barber flown in from Tacoma, Washington, to San Diego, where the team is continuing its nine-game road trip, to tighten up Servais' look.
"I told him to be ready for when I get that 50th save because I want you to fly wherever we are to do the haircut to Scott," Diaz said.
Diaz (1.97 ERA) is the youngest pitcher to collect 50 saves in a season, and he continues to add to his franchise record for saves in a season, having surpassed Fernando Rodney's previous record of 48 set in 2014.
With 31 games remaining in the regular season, the right-hander could challenge Francisco Rodriguez's record of 62 saves in a season. K-Rod set that mark in 2008 while with the Los Angeles Angels. No pitcher has had more than 51 saves in a season since Rodriguez's record-setting season.
Rodriguez is the only pitcher to reach the 50-save mark faster than Diaz, doing it in 129 games, as compared to Diaz's 130.
The Mariners enter play Tuesday seven games back in the American League West and 4½ games out of a wild-card spot.