PEORIA, Ariz. -- It was on a backfield at the Mariners’ spring complex, with only a handful of fans, and a few coaches and reporters, looking on, so the sound was distinctly noticeable.

Every pitch Taijuan Walker threw during a batting practice session on Monday against teammate Dee Gordon and others was accompanied by a loud grunt. Think Monica Seles and other tennis players who have let out a loud noise just as they unleashed a serve.

This wasn’t the Taijuan Walker the Mariners were used to seeing -- or hearing, anyway -- back when he pitched for the Mariners in his first go-round with the club from 2013-16.

Old Walker observers weren’t the only ones surprised by the accompanying audio during his mound session. Walker hadn’t grunted through his first BP session the week before or when throwing bullpens as he worked his way back from a two-year layoff due to elbow and arm issues.

But when he needed to ramp it up while beginning to get game ready, the 27-year-old right-hander found himself returning to something he’d picked up from teammates Robbie Ray and Zack Greinke during his time with the D-backs.

“I just feel like I can release a lot more energy,” he said. “I know I’m being aggressive and finishing, and getting out front. I guess the biggest thing is just being aggressive with my pitch, giving 100 percent everything.”

Greinke, a seven-time All-Star and 2009 American League Cy Young Award winner, is one of baseball’s notorious grunters. Justin Verlander and Clayton Kershaw are among the other MLB pitchers who have been known to let people hear them on the mound. Ray began employing loud audible bursts in 2017, which happened to be the year he landed a National League All-Star berth for Arizona.

Walker started gearing up his own grunt game after talking to Ray and -- coincidence or not -- also put together his best season in MLB in ’17 when he went 9-9 with a 3.49 ERA in 28 starts.

He’s thrown just one inning since -- the first frame of the D-backs' season finale in 2019 -- and admits he hasn’t pitched in so long that he didn’t know if the grunting would still be part of his effort or not.

But when the pitches started to fly on Monday, out popped the sound effects.

“It just kind of came out on a couple changeups and curveballs warming up in the bullpen,” Walker said. “Then my first pitch in the live BP, I did it and said, ‘OK, we’re doing it today.’ It just feels natural now. My first live BP I wasn’t doing it at all. But my second one, my mindset was being more aggressive and it just came out.”

Manager Scott Servais, a former catcher, liked what he saw and heard from his returning starter.

“I thought he was getting after it,” Servais said. “He’s added the Zack Greinke grunt. That is new. But I’m OK with it.”

The Mariners will be OK with anything Walker wants to try if he can stay healthy and continue building his arm strength back up. They’re being understandably cautious after such a long layoff, pushing back his projected first start this Thursday and letting him pitch another simulated outing on Friday before likely slotting him into the Cactus League rotation next week.

Walker is gradually building his velocity back up and continuing to work on his breaking pitches.

“His stuff was pretty good,” Servais said. “His secondary pitches have gotten better. They’ve evolved as he’s gotten older. The consistency of them is much, much better. I’m curious to see how he continues to progress.”

Walker signed a one-year, $2 million free-agent deal to rejoin the Mariners because he knew the club could give him the chance to earn a starting spot, while also having the patience to let him return at a reasonable pace.

So far, so good in that regard as Walker is fully on board with the decision to delay his first Cactus League appearance. There are four weeks until the regular season opens, plenty of time to get where he wants to go.

“Everything is really good,” Walker said. “We just want to make sure and not get too far ahead. I felt good Monday and wanted to make sure the next day I felt good and recovered well and I did. So we’re just being cautious, but I’m moving along good. I wouldn’t say I’m too far behind anyone. Maybe a start, if anything. But come Opening Day, I’ll be ready to go.”