Thon battled vision problems for the rest of his career and was never able to tap into the potential he flashed in 1983, when he batted .286 with nine triples, 20 homers, 79 RBIs and 34 stolen bases en route to finishing seventh in the National League Most Valuable Player voting.
The injuries to Heyward, who suffered a fractured jaw, and Astros rookie Max Stassi, who was hit in the face by a pitch in his second game in the Major Leagues later that night, are part of the game, Thon said.
"You have to learn from it and be ready, you know, because you're so close to the pitcher and it's going to happen," Thon said. "You have to learn to have good balance, but you cannot shy away from the pitch, because you won't be able to hit. They have to deal with it."
While speaking Thursday afternoon from Puerto Rico, Thon said he hadn't heard what happened to Stassi, who was struck in the shoulder and face Wednesday in Arlington. The catcher was released from the hospital Thursday after X-rays and a CAT scan showed no fractures.
Thon wasn't as lucky.
A Torrez fastball broke the orbital bone around his left eye and ended his 1984 season only five games in. He came back in '85, but continued to suffer vision and depth-perception problems. He went on to play 10 more seasons with the Astros, Padres, Phillies, Rangers and Brewers, but was never the same.
"When I got hit, I was a .280 hitter, and I went down to .240-something, .250, .260," he said. "I learned to play the best I could and forget about what I could have done, because in the beginning, I was a much better hitter before I got hit.
"I couldn't see the ball very well after I got hit in my left eye. I had to make adjustments, and open up a little bit and see the ball better. It's tough to do that in the big leagues, but I did manage to play 10 [more] years."
One of the things Thon said he learned is you can't lean out over the plate expecting a pitch on the outside corner. That alters your balance and makes it harder to get out of the way of a pitch that's headed for the body.
"When I was younger, I used to try to cover both sides of the plate, and really, the outside part of the plate, it's tough to get," he said. "I will tell you, when you get hit, you're leaning toward the pitch and you're not ready for the inside pitch. They're going to have to make those adjustments."
The adjustments Thon had to make were more about his altered vision than any apprehensions he had mentally about getting back in the box. He was hit by a pitch only nine times in 4,871 career plate appearances.
"My shoulder used to be closer to the plate, and I liked the ball middle-in when I was younger, and after I got hit, I learned how to hit the other way, and the inside pitch I would let it go," he said. "That's the way I made adjustments. I couldn't see the inside pitch the way I used to."
Thon was asked what advice he would give Heyward and Stassi.
"One of the things is to be able to be a good hitter, you cannot shy away," he said. "That's the one thing. But at the same time, you have to be able to get out of the way. That's a fine line that you have to have that ability. Sometimes you're going to get hit, but you don't want to get hit in the head."
Thon, 55, remains active in baseball and owns a Puerto Rican Winter League team in Santurce. His son, Dickie Joe Thon, was selected by the Blue Jays in the fifth round of the 2010 First-Year Player Draft and is playing for short-season Class A Vancouver of the Northwest League.