After losing four Division I-bound pitchers to graduation, Conestoga wasn't expected to be one of the area's top-tier baseball teams this season.

Now, after Thursday's 13-3, five-inning romp over Methacton in a PIAA Class AAAA state quarterfinal at sun-baked Neumann University, the Pioneers are part of the final four.

"To be honest, I didn't think we had this potential when we started the season," third baseman Shea Rosadino said. "I don't think anyone believed we would do this well. But we're here."

Monday, at a site and time to be determined, Conestoga will face Seneca Valley. It is the Pioneers' first trip to the state semifinals since 1985.

"This team is a team in every sense of the word," Conestoga coach John Vogan said after a contest that lasted 1 hour, 56 minutes. "We all work together. That's why we've been so successful."

Rosadino, a 5-foot-7, 160-pound senior and leadoff man, keyed a 14-hit attack with a 3-for-4 effort, including a pair of triples. He knocked in two runs and scored twice.

For the first half of the season, while he nursed an injured right shoulder, Rosadino served as a designated hitter.

"It wasn't fun for me," he said. "I like playing the field. I've played shortstop most of my life."

Ahead by 4-2, Conestoga, District 1's runner-up, broke the game open with a nine-run fifth inning.

Rosadino sent starter Joey Casselberry packing with an RBI single to center field. The Pioneers (20-4) collected eight hits, all singles, in the frame.

Brian Cizek (two runs) and No. 9 man Tom Richter (2 for 3, 3 runs) each added a two-run single in the outburst. Luke Mogle brought on the mercy rule with an RBI single to right that drove in Richter.

Rosadino, who will play baseball at the University of Scranton, had opened a three-run first inning with a triple down the right-field line.

"[Casselberry] hung a curveball, I sat back on it, and I punched the ball to right field," Rosadino said. "The ball went further than I expected."

Casselberry, a junior, allowed seven runs (all earned) and seven walks in four innings of work.

"His stuff at the end of the game wasn't the same as it was in the beginning," Methacton coach Paul Spiewak said.

The Warriors, who had placed fifth in the district tournament, closed with a 17-11 record. They reached the state quarterfinals for the first time.

Conestoga   31009 - 13142

Methacton   00210 - 351

WP: Adam Rusenko. LP: Joey Casselberry. 2B: M-Nick Strizziere, Clayton Harwick. 3B: C-Shea Rosadino 2, Scott Williams.

Contact staff writer Rick O'Brien at 610-313-8019 or robrien@phillynews.com.