He never lost consciousness, so he can play it all back in his mind with crystal clear clarity: getting smacked in the right temple by the comebacker, hearing his neck crack as he hit the ground face first, wondering if he'd ever walk again.
He recalls the fear that gripped him on his way to the hospital, where doctors performed emergency surgery, inserting two pins into the cracked C-1 vertebra and attaching a small metal plate to the back of his neck.
Despite those frightening memories, Nicasio said he's not the least bit scared about facing hitters again as the hard-throwing right-hander vies for a job in the Colorado Rockies' rotation this spring.
"Yeah, I'm ready to go," Nicasio said after returning to the mound recently to begin getting his body and mind ready for his return to baseball. "I feel the same, same move, everything's the same."
When Nicasio worked his way back onto the field in the Dominican Republic over the winter, he started by pitching behind an "L" screen, and he said he realized right away that he was going to be able to handle seeing hitters in the batter's box again.
"No, I'm not scared," Nicasio declared. "I'm not scared."
He said he has no restrictions on his movement, he can swivel his head and he has no mental block whatsoever from the trauma.
"It's unbelievable," Nicasio said. "A lot of people told me in the Dominican maybe you'll be scared when you go to the mound again to face a hitter. I don't want to change my mind. I'm not scared. I want to pitch in the game. I want to compete again."
Nicasio's remarkable calm and his rather rapid recovery both mentally and physically from that horrifying comebacker last summer amaze his teammates.
"I always knew he was a tough kid coming up," Troy Tulowitzki said. "At the beginning, I always said I liked his presence on the mound, but to go through what he's been through and to be able to say he's ready to go? I don't even know if I could do that. I've got a lot of respect for that kid and I hope he has a great year and it would be a great story.
"I would be probably the first one to admit it, if that happened to me and I had to go out there and throw again, I'd be timid," Tulowitzki said. "But he says he's not."
Left-hander Jorge De La Rosa, who's recovering from Tommy John surgery, played catch with Nicasio in Denver last month when they were in town for the team's annual fan festival, and he came away equally impressed with Nicasio's fortitude.
"He's looking very good," De La Rosa said. "I think he will be good and he will help this team this year -- a lot."
And when that first comebacker leaves the bat, Nicasio said he'll be ready. After all, he said plenty of line drives whizzed by his head over the winter and he said he didn't flinch once.
Nicasio takes solace in knowing he's only been hit in the head once, on Aug. 5 in Denver.
"It's not every day, just that once," he said. "I remember when the ball hit me. When the ball hit me, I'm gone, I hit the dirt. I talk to Doogie (Rockies trainer Keith Dugger), he saw my neck and I remember everything. In the hospital, no. In the hospital, gone. I don't remember much."
Except waking up and realizing how close he had come to dying and wondering whether he'd be paralyzed.
"The last three days in the hospital, I think I didn't have power in my body, I can't move my neck," Nicasio said. "I can't move. I think, 'Oh my God, what happened?' A lot of people were talking about maybe you can't walk anymore. That's scary."
Eleven days later, Nicasio returned to Coors Field wearing a brace to stabilize his neck and received a standing ovation when he stepped out of the dugout with his mother, who had flown in from the Dominican Republic, and waved to the crowd during the second inning of a game against Florida.
"When I saw him like a week after that walking in the clubhouse, I knew it wouldn't take him too much time to get back," closer Rafael Betancourt said. "He has a great passion for this game. That's why he's already back doing what he's doing. I'm very happy for him. He's a great kid and he's a big part of our team, too."
Yet, Betancourt has also admonished those around Nicasio to not dwell on the injury or ask him about it.
"It's hard to pitch and it's going to be harder if every time you go out there you're going to think about what happened," Betancourt said. "I think he's mentally preparing himself to do that and I think he's going to be fine.
The hardest part of Nicasio's recovery was the lack of a blueprint for his return to baseball.
Dugger said he had never seen an injury like this in baseball. A fracture of the C-1 vertebra is usually associated with "diving accidents in a shallow pool or car accidents" and most victims are either paralyzed or killed.
Nicasio started with physical therapy and eagerly worked his way back to the mound, where he was thankful to find peace, not fear.
More than anything, he wants to go on like it never happened. He wants to make a name for himself as more than just the guy who broke his neck in a major league baseball game.
Maybe one day, someone might see the scar and ask him what happened, and then he'll know his legacy is more about his accomplishments than the accident.
If his nasty fastball can be what it was before he got hurt and all goes well over the next six weeks, Nicasio is projected as the Rockies' fourth or fifth starter.
"I don't care if I'm No. 5, No. 1," Nicasio said. "I'm working for the rotation, whatever the number."