Purdy jumped out to a 1-0 lead in the fourth inning when Reese Stevenson doubled and scored on error.
The Wildcats responded with three runs in the top of the sixth inning.
Kreg Meyers singled and scored on Trey Rose's triple. Rose scored on a double by Ricky Nichols and Nichols scored on Ben Makela's single.
"We battled," said Purdy coach Joshua Hughes. "I thought we had a good chance to beat Cassville this year. We just came up short. Reese, I thought pitched the best game of his career."
The Eagles put a scare into the favored Wildcats in the bottom of the sixth.
With one out, Stevenson reached on an error, Austin Hancock and Cody Hall walked to load the bases. Cameron Terry flew out to center field to score on Stevenson. Devon Bennett singled to center field, but Hancock was thrown out at the plate trying to score from second.
"Baseball is a game of breaks," said Hughes. "Nine times out of 10, Austin scores on that play. We had a chance to win at the end. We just need to keep battling."
Purdy travels to Clever on Thursday. First pitch is set for 5 p.m.