Third quarters don’t decide games, but this one was a demo model of why Punahou is the best team in the Interscholastic League of Honolulu.

The Buffanblu shut down Saint Louis’ offensive threat to begin the second half, then drove 97 yards in 12 plays and put the game out of reach in a stunningly easy 43-14 win Friday night at Aloha Stadium.

Third-ranked Punahou improved to 3-0 in league play (4-1 overall) while Saint Louis dropped to 1-1 (2-3 overall). It was a wake-up call for the Crusaders, who had averaged 46.5 points per game against elite competition. Instead, it was Punahou’s polished spread offense that hit hard and often.

Larry Tuileta was near perfect, passing for 356 yards on 21-for-25 accuracy without an interception.

Eight of his spirals went to sophomore Kanawai Noa, who had 198 yards and two touchdowns.

“They’re very talented and they run their offense effectively. That’s a great sophomore receiver,” Saint Louis coach Matt Wright said. “But a lot of it came down to having stupid mistakes, having the wrong coverages. The penalties, sometimes it’s discipline issue we’re constantly trying to remedy. We can’t keep putting our offense in a shootout match every time.”

Punahou’s defense was powered in part by linebacker Isaac Savaiinaea and defensive end Canton Kaumatule, both back from early-season injuries.