SURPRISE, Ariz. -- Royals left-hander Danny Duffy, who will make his spring debut on Sunday afternoon against the A’s, is making one guarantee this season: He will not be making any guarantees.

“I think the days of me going full Rex Ryan and making guarantees or goals for myself are behind us,” Duffy said. “I’m in a better place now, a good place. Now let’s just let it play out.”

Of course, this will be a pivotal year for Duffy, now 31, and in the fourth year of a five-year, $65 million contract. Nagging injuries began afflicting him soon after he signed that deal, coming off a 2016 season when he went 12-3 with a 3.51 ERA and 188 strikeouts in 179 2/3 innings.

Those injuries have limited Duffy to 75 starts in the past three seasons, and his ERA for the last two seasons were disappointing: 4.88 in 2018 and 4.34 in ’19.

But Royals general manager Dayton Moore has said repeatedly this offseason that he believes Duffy’s maturity level has evolved to the point that Duffy is ready for a renaissance on the mound.

“We know the talent is still in there,” Moore said.

Duffy is flattered when told this, but cautious in his response.

“I really don’t want to go there, because every time I do it just brings ridicule,” Duffy said. “I’m just going to let the season play out and do what I do.”

Kansas City manager Mike Matheny echoed Moore, and said he also believes something special is about to happen with Duffy in 2020.

“He just seems extremely motivated to be what Dayton is saying he’ll be,” Matheny said. “He is wanting to do and be something different this year.”

Duffy may not ever again be the dominating hurler he was in 2016, with a fastball that could touch 98 mph and a near no-hit game against Tampa Bay during which he set a franchise record with 16 strikeouts.

But Duffy hasn’t forgotten about that game or that season, and he said that player is still inside him.

“Of course I believe that,” he said. “A lot of things have happened the last few years. I’ve been awful in stretches. I’ve been hurt. I’ve had bad things happen. I’ve got a pretty clear head at this point. I can handle anything thrown my way right now.”

And here’s the intriguing part: Duffy’s velo, which sat around 92-93 mph last season, might be better this spring.

“I still think there’s some [left] in the tank with the fastball,” Matheny said.

Duffy agreed and noted that the ball seems to be coming out of his hand with ease this spring.

“It’s coming out really hard,” Duffy said. “I feel like I got a couple ticks more. We’ll see. I haven’t had a [radar] gun on me yet. I asked Cal [Eldred, Kansas City’s pitching coach] once, and he didn’t want to tell me. But the ball is coming out of my hand really good.

“You can kind of gauge where you’re at just by eyesight. But we’ll see. I’m done making predictions.”