The Eagles were in the game until late in the third quarter, despite managing only 17 yards and zero first downs the first two periods.
But after Estancia seized then surrendered the momentum immediately after the homecoming intermission, Beckman, the third straight Pacific Coast League entry and Irvine-based school to get the best of the Eagles, scored 21 points in a span of six minutes, 25 seconds.
The late scoring blitz sealed the win and sent the Eagles reeling out of a preleague season that Coach Mike Bargas fully anticipated would challenge his squad.
"I've said this is a little bit of a proving ground for us," Bargas said. "[The Patriots are in our CIF Southern Section Southern Division] and if we want to get to the next level, we've got to be able to compete against these guys … Hopefully, this is a lesson for us and we hope it's a tipping point for us when we go into league."
The Eagles begin Orange Coast League play Friday against Laguna Beach.
Estancia was not in the Patriots' league before halftime, though senior safety Matt Carlyle recovered a fumble and intercepted a pass in the first half to help keep the Eagles close.
Estancia, however, needed just three plays after the second-half kickoff to cross midfield and, after just four snaps, they had their first two first downs of the contest.
After quarterback John Diego hit Miguel Mejia for 10 yards on third-and-seven, sophomore tailback Robert Murtha ran seven yards to the Beckman 24-yard line on first down.
But a pair of subsequent runs lost seven yards and the Eagles were forced to punt.
After senior Cameron Collins returned Beckman's ensuing punt 34 yards to the Patriots' 22, the Eagles made their first visit to the red zone. But on fourth-and-nine, a pass fell incomplete and the Eagles never seriously threatened again.
Murtha finished with 68 yards on 24 rushing attempts, 17 of which produced no more than three yards.