"I think he realized the gig was up and he kind of ran into me and I grabbed him and got him on the ground,” McSorley said.
He continued to hold him down until police got there.
Pittsburgh police confirm they arrested and charged the man, 42-year-old David Samuel.
They say he's responsible for at least two package thefts at an apartment building on Melwood Avenue.
McSorley shared a video with WPXI showing Samuel allegedly in the act.
He said he's not sure he would do something like this again and has a message to the suspect.
"I just hope whatever is causing him to do this.... I hope he can get his life together," McSorley said.
McSorley knows a thing or two about defending himself. He coaches and trains several professional boxers.