That one at-bat was his only at-bat of the 2012 season.
It was Stage 1 and caught early. But the lump had been a fast-growing tumor that had to be taken out. (One comment on the report scared them: "Unfavorable.") There would be chemotherapy and radiation instead of daily batting practice.
"It was rough watching the guys have fun, win games," Coleman said. "I was just trying to stay awake on the bench watching. I fell asleep a couple of times."
He did stay on campus while traveling to the twice-monthly chemo sessions. His oncologist at the Hospital of the University of Pennsylvania had recommended staying in school, that "bubble-wrapping him" at home might make him depressed.
"I think our team fed off of how he handled all that," said West Chester coach Jad Prachniak.
Even the day he got the news, Coleman's parents asked if he wanted to go to dinner with them. He said he'd just as soon eat with the team before he joined them.
Coleman was able to dress for home games and shagged balls when he had the energy, getting to as many practices as he could. As it turned out, he can't know how much he would have played anyway as a freshman. A veteran group, the West Chester Rams began winning games and never stopped until they won an NCAA Division II national title.
Coleman drove to the championship game in North Carolina with his parents, and there they found some good-luck signs, literally. The field itself was named Coleman Field. It was located in Brooks Park. Coleman's father's name is Brooks, named for Brooks Robinson, the former Baltimore Orioles great.
The day after West Chester won the title, Coleman had surgery to remove the port in his chest that received the chemo. He still had to undergo radiation but was able to play summer baseball for the Quakertown Blazers in the Atlantic Collegiate Baseball League. He proved to himself that he hadn't lost his feel for hitting, although the radiation still tired him out.
Nobody could have predicted how quickly he would return to the game.
"There was definitely some mystery there," said Prachniak.
"I'm not taking anything for granted," Coleman said. "I was always healthy. I'd never had to worry about my health. Now I was 19 years old, and I already had cancer. It was like, 'Oh, jeez.' "
The TV movie version would have West Chester making a run at another title this season, but it hasn't gone that way. The Rams, younger this time around, needed to do well this weekend at Kutztown and get a little help to make the Pennsylvania State Athletic Conference playoffs. They are 20-23-1 and tied for fourth in the PSAC East.
The script won't have to alter reality to account for Coleman. All scans have shown the cancer was knocked out. He's become a regular as a redshirt freshman, happy that he'll still have four years of eligibility. Mostly a third baseman in high school, West Chester needed him in left field, and he's proven himself at his new position.
After going 4 for 6 Tuesday against Chestnut Hill, Coleman was hitting .354, easily tops on the team.
"The ball looks like a beach ball," Coleman said this week. "When I'm really comfortable, I feel like I can't get out, that I can hit anything."
"It's pretty impressive," his coach said. "This is his freshman year. His first year of action, he's been pretty steady. I honestly feel from a baseball standpoint, I think he's just scratching his potential. Tyler is a little bit raw, but you can see him get better week to week, game to game."
He's a ballplayer from a family of ballplayers. He looked back at that one game he played last year and said to his parents, "You knew I had cancer during the game didn't you?"
They had waited until later that night when they could get him alone to tell him, his mother said. But Coleman had noticed his father hadn't said a word right afterward about him swinging at a bad pitch.
Later on, Coleman admitted he hadn't been entirely honest when he'd assured his mother the chemo wasn't too bad.
"It's the worst thing I ever went through," he later told her. "I just didn't want to wig you out."
He can usually forget day-to-day that he ever had cancer. But it never leaves him entirely. He knows life can throw curveballs.
"I play as hard as I can," Coleman said. "You never know."
Contact Mike Jensen at email@example.com. Follow @jensenoffcampus on Twitter.