DUNEDIN, Fla. — Those who have watched Marco Estrada’s outings closely this spring have noticed a slight difference in the Toronto Blue Jays starter.

Never one to blow you away with his velocity, Estrada’s fastball has been coming out of his hand with a little more zip, sitting at 90-91 m.p.h. during his three outings. He hasn’t averaged more than 89 m.p.h. on his heater since 2013. But it appears the pitch could have a little more muscle this season.

“It’s actually pretty simple,” Estrada says when asked if anything’s different. “My back isn’t locked up.”

You probably know that Estrada battled a lower back injury throughout the 2016 season, pitching through it to make 29 starts and three more in the playoffs. But the proud 33-year-old never quite let on about how much pain he was in, and how much it limited him on the mound.

“It was really bad,” Estrada says. “I was never 100 per cent at any point last year. And I knew you could see it in my velocity. I know I was seeing it. I wouldn’t want to look back at the gun during my starts because I knew it wasn’t good. There were a lot of days where I was like, ‘Man, I’m not feeling great out here.’”

On start days last season, Estrada had to endure through a long, arduous pre-game process to get his back loose enough to pitch. He’d take painkillers, let trainers stretch him out, and have his back both cooled and warmed with different rubs. He also received a number of cortisone shots throughout the year, which helped, if only temporarily.

Sleeping was also an issue, as Estrada got used to long, restless nights. Halfway through the season he had his mattress switched out for a much firmer option in an effort to get him more shuteye. It helped a little.

At the Letters Ben Nicholson-Smith is Sportsnet’s baseball editor. Arden Zwelling is a senior writer. Together, they bring you the most in-depth Blue Jays podcast in the league, covering off all the latest news with opinion and analysis, as well as interviews with other insiders and team members.

Estrada suffered the injury in spring training, and actually started the year on the disabled list because of it before making his first start of the year on April 10, shutting out the Boston Red Sox over seven innings. He was still carrying the injury, but Estrada hates missing starts and was determined to pitch through it for as long as he could. There were good days and bad. But when his turn in the rotation came up, no matter how he was feeling, Estrada was pitching.

That led to some difficult moments. There were times when he would jog out to the mound and wasn’t able to bend over to pick up the ball when he got there. He remembers one particular start vividly—July 2 versus Cleveland at Rogers Centre. Of all the good and bad days, that was decidedly a bad one.

But he didn’t want to let his teammates down, so he took his medication, spent hours getting limbered up with trainers, and went out there. He threw his first pitch, a called strike, at 83.7 m.p.h.. PitchFX recorded it as a changeup. It was actually a fastball.

“I was like, ‘Oh man, what am I doing out here right now?’” Estrada says. “’It’s gonna be a long day.’”

At one point, Blue Jays third baseman Darwin Barney tried to throw the ball back to Estrada after an out but had it slip out of his hand and short-hop in front of the mound. Unable to bend over and catch the low throw, Estrada just let the ball hit him and roll away, before walking over to it and gingerly crouching to pick it up.

“I was actually trying to kick it up to myself,” Estrada says now with a laugh. “I missed.”

The Blue Jays put Estrada on the 15-day DL shortly after that start, but thanks to the all-star break and a pair of off-days following it, the Blue Jays were able to manipulate their rotation and get by without him. He returned to the mound less than three weeks later, allowing two runs over six innings in a loss to Seattle.

Remarkably, Estrada’s numbers hardly suffered as he pitched through the injury. He finished the year with a 3.48 ERA, not much higher than the 3.13 number he posted a year prior. He threw just five less innings than he did in 2015, led the league in H/9 for the second year running, and actually increased his strikeouts, pitching to an 8.4 K/9, up from 6.5 the previous years.

“I’m glad I was able to pitch for these guys,” Estrada says. “It was definitely a grind—but I got through it.”

He paid a price, too. After the season, Estrada went home to California and got together with some friends for an afternoon of trap shooting. Everyone took their volleys, trying to pick off the clay plates launched in the distance. But when it was Estrada’s turn he could only fire off a few rounds of ammo before he had to hand off the gun and sit down.

“Just standing there for two minutes, I was in so much pain,” he says. “It was bad.”

It took a while before he felt like himself again. Estrada says he didn’t turn a corner with the injury until January. He spent much of his winter working diligently on his core, modifying his usual gym routine to engage his abdominal and back muscles more than he normally would. Any exercise he once did sitting he now does standing or kneeling. That’s on top of the bear crawls, carries and core routine he performed regularly. It was a lot of work.

“You always work hard in the off-season,” Estrada says. “But this was different. I (pushed) through those workouts for a good two months.”

He also switched out his bed at home in California, buying a brand new sleep number mattress that lets him adjust its firmness on a scale that tops out at 100. He’s never set it lower than that absolute maximum.

“It’s rock hard—it’s awesome,” Estrada says. “My old one, I used to sink into it. It was pretty soft. All this stuff I’ve been doing has helped me out a lot. My back’s feeling much, much better. And it’s obviously showing.”

When Estrada made his first start of the spring, he was hoping to hit 87 m.p.h. with his fastball. He wasn’t throwing as hard as he could; he wasn’t sure how his back would respond to all that off-season work as he hadn’t pitched in months. He certainly didn’t expect to be at his best. But then he looked back at the scoreboard after a few pitches and saw a big fat 90 pop up from the radar gun.

“I’m going, wait, what?” Estrada says. “And I’m feeling like there’s more in the tank. I’m out there just trying to work on stuff. I’m throwing nice and easy.”

Look, Estrada’s not going to suddenly morph into a power pitcher. But a little more zip on his fastball can only make his devastating changeup that much more effective. And, most importantly of all, Estrada’s feeling healthy for the first time in a long time.

“That wasn’t fun last year—there were days when I felt really bad,” Estrada says. “But I feel back to normal now. My back’s feeling so much better. Hopefully it turns out with better results.”