After Serna is switched to QB, St. Bonaventure lights it up

While munching on a carne asada taco at a coaches’ barbecue, Ventura St. Bonaventure’s youthful first-year football coach, Todd Therrien, made a decision that proved to be a decisive moment in helping the Seraphs (13-1) earn an invitation to Saturday’s CIF state Division III championship bowl game.

Therrien switched Casey Serna from wide receiver to quarterback during the Seraphs’ off week in October. Serna had won the job during the summer, but an injured thumb on his non-throwing hand in a preseason scrimmage kept him out. Even though the Seraphs were 4-1 under quarterback Tony Macarena, Therrien sensed that Serna’s athletic ability could raise the offense to another level.

Serna fulfilled his potential last Saturday, when he rushed for 140 yards and passed for two touchdowns in St. Bonaventure’s 42-28 victory over Newhall Hart in the Southern Section Northern Division championship game.

Serna’s versatility, combined with all-star running back Darrell Scott’s big-time talent, gives St. Bonaventure an imposing offensive duo for its bowl game against Modesto Central Catholic (11-1-1) at 11:30 a.m. at the Home Depot Center.

“Casey Serna is amazing,” Therrien said. “He’s changed everything.”

Serna was known more for his exceptional baseball skills on campus. He can throw a fastball 92 mph. He had an 8-1 record and batted .429 with 16 stolen bases. When he wasn’t on the mound, he was playing shortstop. Former Cal State Fullerton coach George Horton thought so highly of Serna that he signed him to a letter of intent last month, part of his first recruiting class at Oregon.

The way Serna has been running St. Bonaventure’s spread offense, Oregon football Coach Mike Bellotti might be calling him too.

“In this day and age of spread quarterbacks, there’s nothing that kid can’t do,” Therrien said.

Hart coaches were stunned that Serna was able to run at will against them, taking off from shotgun formation when his receivers were covered.

“He hadn’t shown a lot of that in previous games,” Hart Coach Mike Herrington said. “He showed his athletic ability.”

Serna finally has become comfortable playing quarterback. He hadn’t played the position since he was 9.

“At first, it was mostly instincts,” he said of his play after the midseason change. “Now I have a good feel for what I’m doing, what to read and what to look for.”

A turning point for Serna came when one of his offensive lineman told him, “We got you.”

“At first, I kept looking at the offensive line,” Serna said. “I was worried about people getting through. But when I started having trust in them, I started to look to the receivers.”

At 5 feet 11 and 180 pounds, Serna’s mobility and quick decision-making seem an ideal fit for the shotgun formation. If teams focus too much on trying to stop Scott, the top-rated running back prospect in the nation, then Serna is ready to make them pay.

St. Bonaventure is 9-0 with Serna as its starting quarterback.

“The bottom line is Casey gives us a whole different dimension to the offense,” Therrien said.

With support from former St. Bonaventure quarterback Jack Swisher, the Seraphs’ offensive coordinator, Serna is learning when to run and when to pass.

It also helps that Therrien has proven to be a strong leader for a program that lost its charismatic coach, Jon Mack, who left last spring to take over the team at Ventura College.

It turns out Mack taught his ex-player and ex-assistant coach well, because Therrien, 28, has held up under the pressure and scrutiny that comes with the high-profile position.

Most of all, his insight as to what Serna could provide to the offense has re-energized the Seraphs’ season.

“I feel like everybody has jumped on my back,” Serna said of his leadership role. “I’m telling them, ‘Let’s go.’ ”

eric.sondheimer@latimes.com