The 6-foot-7 Schirmer scored 26 points, grabbed 17 rebounds and blocked seven shots in leading the fifth-seeded Pirates to an 83-65 victory over third-seeded Valle Catholic.
Schirmer also pulled down 17 rebounds in a first-round victory over Cobden, while also scoring 18 points and collecting six steals. He later scored 20 points in a semifinal loss to Chester.
Schirmer finished as both the tournament's top scorer and rebounder, averaging 21 points and 14 rebounds. He averages 14 points and 11 rebounds on the season.
Schirmer suffered knee injuries in both his freshman and sophomore years that limited his playing time on the JV level. He's playing varsity for the first time as a junior.
"This is actually the first year that he's been healthy, and it's shown," Perryville coach Justin Dreyer said. "He's had a heck of a year for us."
Dreyer said Schirmer has dropped 60 pounds from last season.
"I think that's part of the reason that's helped him stay healthy," Dreyer said. "He's able to move, and he has great hands for a big guy and a soft touch around the basket."
Schirmer is shooting 57 percent from the field and 75 percent from the free-throw line.
The Pirates doubled their season win total during the week, improving to 4-9.
"He's got to play good for us to play good and score," Dreyer said. "Everything usually goes through him."