Stassi left the game and appeared to be bleeding from his nose. The 96 mph fastball from Scheppers appeared to hit Stassi in the shoulder before glancing off his face. It came with the bases loaded and forced in the game-tying run.
Stassi went to the hospital and will remain there overnight for observation.
"He's at the hospital right now and we will get a full report when they run all the tests, but we do not have any updates right now," Astros manager Bo Porter said. "But it was a scary situation. I think it hit him in the shoulder and then in the face, so that probably lessened some of the blow. It was frightening. They brought him straight in and took him to the hospital."
It was the second consecutive batter Scheppers hit after beaning Houston third baseman Matt Dominguez to load the bases.
"It's one of those pitches that got away," Scheppers said.
The Rangers went on to win 5-4.