Chicago — The worst part for Daniel Norris, aside from the post-surgical pain and the four months of arduous physical labor in the oppressive, central Florida heat, was the feeling of being disenfranchised.

Because he wasn’t yet able to drive himself in the early days following groin surgery, he had to stay at a tiny hotel close to the Tigers’ spring training facility in Lakeland. He couldn’t go out at night. It was get up, spend the entire day at the facility doing physical therapy and other rehab-related work, eat and go back to the hotel — rise, rinse and repeat, day after day.

“I was going stir crazy,” he said. “It was a tough process. Weird being away from everything. I didn’t feel like a baseball player.”

That he’s made it back to the Tigers — he will make his second start on Friday against the Cardinals at Comerica Park — well, that didn’t seem feasible back in late June and early July when he finally started throwing again.

“I had three setbacks,” he said.

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The first one was by far the worst. It was during his third bullpen session, and it was the first time he tried to throw breaking balls.

“It was the first slider I threw,” he said. “And I dragged my leg more and (the groin) wasn’t freed up enough. You could hear it like snap and tear. I just started screaming. I went inside and by the time I got my pants off, with was swollen out to here.

“For like 24 hours I didn’t know what was going to happen. It was all black and blue.”

He thought he had just undid the surgery and two months of rehab work with one throw. But Corey Tremble, the Tigers minor league rehab coordinator, told him he’d ripped scar tissue.

“He said it was the worst scar tissue tear he’d ever seen,” Norris said. “He told me, ‘We’ve got to be patient.’ But it sucked because I was feeling really good.”

Tremble also told him the horrific first tissue tear was a blessing in disguise, kind of like ripping a Band-Aid off. Yeah, it hurt like the devil, but it accelerated the process. That scar tissue was going to have to break up eventually.

“I had two more tears like that, but not nearly as bad as the first one,” Norris said. “I had to miss a day or two of throwing, but after that — I mean, I can still feel a little tissue in there, but it’s a lot easier now.”

Once he got back on his throwing program and making rehab appearances, the recovery went quickly. Quicker, even, than Tigers’ manager Ron Gardenhire and pitching coach Rick Anderson thought possible.

“Yeah, once I got back on the mound, it just kind of took off,” Norris said. “Gardy and Andy told me they didn’t expect me to come back that quickly. But it’s just a tribute to gritting your teeth and getting through it.

“I feel like the scar tissue was kind of a mental block for me, because it hurt real bad. But I am finally over that and now I can just worry about pitching.”

Norris made his return last Saturday in New York and he was impressive. Even though his fastball velocity is still in the low-90s, he kept a powerful Yankees lineup off-balance. He pitched four perfect innings before a two-run home run by Gleyber Torres and cramps in his calves ended his night in the fifth inning.

“My breaking balls were good and my fastball is still true and has a little life on it,” he said. “I’m still getting some swings and misses, even at 91 and 92 mph. I’m learning how to pitch and when the 95 mph comes back, I am going to be better for it.

“I feel like I can absolutely compete at this level right now.”

About the cramps. This has happened to him a lot over his career, even when he’s getting regular work. It happens because of his intensity, because of his desire to throw the fire out of each and every pitch.

“Every time I throw a little extra, I go up on my toes, by accident, and I start using muscles I’m not really used to,” Norris said. “I think I was doing it on my slider. I was throwing it and they were fouling it off. I was throwing good sliders and they kept fouling them off. So I said, ‘I have to make it nastier.’

“So I started trying harder and that’s what happens when I start grinding on it too hard.”

Without knowing he was doing it, he would come up on his toes during his delivery, straining the calf to the point where it cramped.

“The weird thing is, I came in after the game and my toes were all cut,” he said. “I don’t have long toe nails or anything like that. But I was just squeezing so hard.”

There were no lingering effects from the cramping. He threw a long bullpen session before the game here Tuesday and felt great. He said he made some adjustments to his arm angle which he liked. He doesn’t expect his velocity to get back up to 95 mph this year; he’s accepted that the process will be gradual.

“I guess after I rehabbed it (before agreeing to surgery) I was kind of looking for a quick fix,” Norris said. “I will do this and it will get my 95 back. But it’s a process. Talking to Corey, it’s not something that’s going to happen overnight.

“But having said that, I was like at 88-90 before the surgery. It was bad. If there is any consolation, it’s that I am able to hit 92-93 and that wasn’t happening before. I can even tell by my stride length that it’s freeing up. My arm strength is going to come. Might not be this year, but it’ll definitely be there next year.”

Norris paused a beat and then said, in his ever-optimistic way, “I could wake up and throw 95 tomorrow.”

Would that be any more improbable than him getting back into the rotation for the final month of the season?