PEORIA, Ariz. -- It was only the first bullpen sessions of Spring Training, but catchers mitts were popping on Friday at Mariners camp as hard-throwing closer Edwin Diaz and burly new setup man Juan Nicasio fired sizzling fastballs side by side for a 10-minute session.
The 23-year-old Diaz already looks sharp and with good reason. The youngster said he tossed seven bullpen sessions and a live batting practice back home in Puerto Rico before arriving in Peoria, far more than most pitchers usually throw before they arrive.
"I like to come 100 percent ready to go," said Diaz, who tied for fourth in the American League last year with 34 saves while posting a 3.27 ERA and 89 strikeouts in 66 innings.
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Diaz has already latched on closely to Nicasio, a 6-foot-4, 255-pound veteran who signed a two-year, $17 million deal with the Mariners as their primary free-agent acquisition. The 31-year-old compiled a 2.61 ERA with six saves while striking out 72 in 72 1/3 innings over 76 appearances, which put him in a first-place tie for most in the National League.
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"He was one of the best relievers last year and for the last couple seasons," Diaz said. "He's a great guy and I've talked a lot to him already. I want to know about him and try to have him help me a lot this season."
Diaz, who turns 24 next week, is no longer the skinny 6-3, 165-pound rookie who showed up with Seattle in 2016. He added 10 pounds from last year to 195 over the offseason, though he says he lost seven of that recently due to a bout with the flu in Puerto Rico. But his frame clearly is filling out, and he intends to grow his game, as well.
The Mariners took him out of the closer role briefly in the middle of last season when his mechanics got sideways, and he says the lessons learned have stuck with him since.
"Today I missed a couple pitches and I made the adjustments in my mind," Diaz said. "That's what the pitching coach taught me. They say I'm young, but I want to think like an old guy. Try to refocus and do my job."

Healy expected to rejoin team Monday
After undergoing surgery Wednesday in Philadelphia to remove a bone spur in his right hand, first baseman Ryon Healy will return to the Mariners on Monday when position players are due to report for physical exams.
The Mariners are hopeful the 26-year-old can be ready by the start of the regular season on March 29, but it's a tight window, as he's expected to need 4-6 weeks of recovery time. Opening Day is six weeks away.
"You won't see him out on the field for at least 10 days to two weeks before he does any defensive work," Mariners manager Scott Servais said. "We want to let this thing heal and quiet down."
• Healy out 4 to 6 weeks following hand surgery
The Mariners' medical staff has put together a workout program to keep Healy in good shape while his hand heals, but Servais said he couldn't put any timeline yet on when the young slugger might be able to start swinging a bat.

Short takes
• Reliever Ryan Garton, who had hip labrum surgery in October, will need a couple more weeks before he begins throwing. Garton and Hisashi Iwakuma are the only pitchers not scheduled for bullpen sessions in the first three days of camp.
• Felix Hernandez will be in the group of nine pitchers who will throw their first bullpen sessions in Saturday's workout, which starts with stretching at 11:20 a.m. MT. The bullpen groups begin at 12:10 p.m. and will include starting candidates Erasmo Ramirez, Marco Gonzales, Max Povse and Rob Whalen along with relievers Nick Vincent, David Phelps, Tony Zych and Chasen Bradford.
• The Mariners have pondered converting Sam Moll into a starting candidate, but the lefty will remain as a reliever this spring, which is the role he filled for the A's in his first MLB stint late last season.
Servais said Casey Lawrence, another swing-man candidate, will also stay in the bullpen, while Povse and Christian Bergman will be stretched out as starters after pitching in both roles last season.