The Crusaders jumped out to a 3-0 lead in the first inning. Josh Holden was safe on an error, Carson St. Amour singled, and the Crusaders had a double steal to score their first run.
Ryan Gillings and Carson Bleicher followed with doubles to knock in two more runs.
But Three Oaks River Valley clawed back, scoring one run in the fourth and two in the fifth, then scored the winning run in the sixth. MCC, meanwhile, stranded four runners in scoring position.
MCC pitchers Nolan Convertini and Navarre Klint scattered six hits and struck out four.
The Crusaders finished the season with a 27-3 record, a Lakes 8 Conference championship and a Division 4 district title.