30-year-old Francis Kirchner, 37-year-old Charles Bowers and 48-year-old James Groves are accused of taking part in the beating that killed 22-year-old David Sale outside of Citizens Bank Park.
Kirchner was charged with first-degree murder and Bowers and Groves were charged with third-degree murder.
The voluntary manslaughter pleas came after a judge declared a mistrial last month after witness gave testimony that was not supposed to be allowed.
Sentencing is set for December 20th. They face up to 20 years in prison.
Bowers and Groves have been free on bail while Kirchner remains behind bars.