Flintridge Prep scored two runs in the top of the first on a throwing error by Capistrano Valley Christian sophomore pitcher Sam Eichler (10-1).
Kyle McDonald led off with a walk and Royce Park doubled with no outs against the left-hander, who then misfired to first on a come-backer and allowed McDonald and Park to score.
Then the Eagles (20-6-1) began to make things happen in their half of the first.
Park (5-5) made an errant throw to first on a grounder back to the mound with a runner on first. That put runners on first and third before Park, a sophomore right-hander, uncorked a wild pitch to cut the lead to 2-1.
"That's a play that Royce should have made," Cook said. "That play set the tone."
The Eagles, who entered the contest with 119 stolen bases, stole three of their eight bases in the game to help take a 4-2 lead in the second.
A fielder's choice tied the game at 2 before Niko Knechtel doubled in a run to make it 3-2. An infield single by Nathan Antoun extended the lead to 4-2.
"The Eagles got a three-run home run from Jacen Carpenter in the fourth off reliever Steve Fleming to make it 8-2. Flintridge Prep closed out the scoring in the fifth on a run-scoring single by McDonald, who finished with two of the Rebels' five hits.
"We had an up-and-down season. We met some expectations. We made a good run against a good team."
Flintridge Prep received one hit apiece from Park, Connor McCann and Nick Ostiller.