Column: St. John Bosco’s Sean McGrew is running away with it

Start feeling sympathy for any opponent left on the schedule of unbeaten Bellflower St. John Bosco. The reason is running back Sean McGrew has never been healthier, and that means when he gets into the clear, you better have someone very fast to try to catch him.

No. 3-ranked Santa Ana Mater Dei (6-1, 1-1) got a little taste of McGrew’s speed on Friday night. He broke off runs of 45, 81 and 56 yards and finished with 213 yards rushing in 16 carries and scored two touchdowns in a 42-21 rout of the Monarchs at Santa Ana Stadium.

“I’ve had my dose of him for three years,” Mater Dei Coach Bruce Rollinson said.

For the seventh consecutive game, No. 2-ranked St. John Bosco (7-0, 2-0) forced the officials to invoke the mercy rule in the fourth quarter. It’s a running clock when a team opens up a lead of 35 or more points. The Braves led, 42-7 going into the fourth quarter (it had led 42-0 earlier).

It was St. John Bosco’s 18th-consecutive Trinity League victory.

“We knew what we were walking into and knew we’d have to pretty much play a perfect game, and we didn’t,” Rollinson said.

St. John Bosco turned in a flawless performance on defense in the first half that could be shown at football clinics on how to execute in all phases, and the team opened a 28-0 halftime lead. Defensively, the Braves put pressure on freshman quarterback J.T. Daniels. He had just 30 yards passing midway through the third quarter. He ended up nine of 24 for 220 yards and three touchdowns.

The Monarchs didn’t help matters by dropping passes and committing nine penalties for 65 yards.

Offensively, St. John Bosco always had its most dangerous weapon — McGrew — available. His runs set up Cross Poyer, who was used on short-yardage situations and scored touchdowns on runs of one and two yards in the first half.

St. John Bosco Coach Jason Negro continues to be nice to opponents. The Washington-bound McGrew’s only appearance in the fourth quarter was when the Braves needed a punter.

“I don’t think I’ve played a down in the fourth quarter this whole season or carried the ball, which is ridiculous,” McGrew said. “It shows our offense is stepping up scoring tons of points and making my job easy. I’m definitely healthier with less carries. I don’t really have those bumps and bruises like I had last year.”

Although St. John Bosco came in averaging 63.7 points, the defense also leaves a lasting impression. Junior defensive end Jacob Callier had two sacks.

“It’s 10 times better,” he said of the defense this year.

Even Callier is having fun watching McGrew carry the ball. “Every time you see him run, you see a different speed,” he said. “He gets faster and faster.”

eric.sondheimer@latimes.com

Twitter: LATSondheimer