He won 68 games (68-42) over his first 10 years, good enough to tie George Stratts for second on the school's all-time list.
Many of his former players, however, recalled their coach more for his profile off the field.
Nolan Cummings, 18, of Newtown Square, played for Mr. Algeo for four seasons.
"He would always come to our proms," Cummings said of the coach.
This time last year, on the same day Mr. Algeo died, Cummings' grandfather died. Mr. Algeo, Cummings said, was one of the first to offer Cummings comfort. He even went to the funeral.
"I'd consider him as a friend without any hesitation," Cummings said. "He'd drop everything."
Mr. Algeo taught personal and business law and sports management at O'Hara. He graduated from Lansdale Catholic High School and Gwynedd Mercy College.
In addition to O'Hara and Roman, he was the head coach at Phoenixville High School and an assistant coach for his father, Jim Algeo, at Lansdale Catholic.
Mr. Algeo was 98-69 overall in 15 seasons as a head coach.
"Please continue to pray for his family and the many people who held Coach Algeo close to their hearts," the statement said.
Joe McCourt, Roman's seventh-year head coach, played under Mr. Algeo and then coached against him in the Catholic League.
"He was a salt-of-the-earth kind of guy," McCourt said. "He would do anything for his players. If you played for him, he always remembered you."
Faith. Family. Football. Those were Mr. Algeo's big three, said Andrew Gallagher, 17, of Chichester, one of the team's senior captains.
"He treated us like family," Gallagher said. "And he loved Cardinal O'Hara football."
Gallagher called Mr. Algeo a father figure. On the field, he was a tough, no-nonsense coach.
Football "was kind of his life," said Tim Aikins, 16, a senior who transferred to O'Hara from the Haverford School midway through last year to play for Mr. Algeo.
"He wanted to make sure any laziness that was in you was gone by the end of the season," said former player Andrew Houtmann, 19, of Glen Mills.
Houtmann recalled one time when an older teammate was joking around, throwing tennis balls in the locker room. When Mr. Algeo heard of the tomfoolery, he made the team run laps for 30 minutes after practice.
But the next day, Mr. Algeo apologized to the boy he punished. It wasn't personal, Houtmann remembered Mr. Algeo saying at practice. But the time for messing around was not in the locker room or on the field.
"He wouldn't take any of that on his field," Houtmann said.
"He'd scream and holler," said senior captain Nick Mariotti, 17, of Secane.
But at the end of practice, Mariotti said, it was always: "I love you guys. I believe in you. You make me proud."
Players, who gathered at the school Thursday morning in place of their scheduled 8 a.m. workout, remembered Mr. Algeo as someone who made sure everyone around him was happy.
In the hallways, Mr. Algeo was always singing.
"Whatever cool song was popular. He liked 'Turn Down for What,' " Mariotti said with a laugh.
And at proms, winter formals, graduation parties, the coach was always there.
At junior prom this spring, Gallagher said, "he came out dancing with us. . . . He liked to have a good time."
"The players all really liked him," Aikins said. "He was a fun guy to be around."
The captains said the team will not return to offseason practice until after Mr. Algeo's funeral, but the players will likely gather again after the holiday weekend.
Thursday morning, they shed tears and shared memories of their coach, teacher, and friend.
"He always treated us with respect," Gallagher said.
"He made it more our team instead of his," Mariotti said.
Mr. Algeo will leave behind a legacy far greater than wins and losses, the players said. What people will remember about Mr. Algeo, Mariotti said, is "how big of a heart he had."
Known as one of the best high school coaches in terms of getting his football players onto top college teams, Mr. Algeo coached stars such as quarterback Tom Savage, wide receiver Corey Brown, and safety Anthony Walters.
All three had stellar college careers, and Walters is already in the NFL. Savage and Brown are embarking on their pro careers.
"He was just one of those coaches that helps you out so much in high school," Savage said. "You go in there as a 13- or 14-year-old boy, and you leave there as a man. . . . I know all of the [players] really respect him. This is going to be a tough loss for everybody."
Each year, under Mr. Algeo's direction, O'Hara would host a college night. The free event gave junior and senior football players in the Philadelphia area the opportunity to meet with representatives from Division II and III schools.
"He certainly did a lot for his players," said Bonner-Prendergast football coach Greg Bernhardt.
Mr. Algeo had just served as head coach of the East squad that won the state's East-West Bowl Game in Pittsburgh on May 4.
Bernhardt assisted Mr. Algeo at Cardinal O'Hara from 2004 to 2006.
"Danny was one of my good buddies," Bernhardt said. "He taught me a lot. Football was one thing, but Danny was a great overall person. He'll be sorely missed."
Algeo's father, Jim, spent 53 seasons coaching at Lansdale Catholic, including 44 as head coach. Dan Algeo was an assistant to his father after graduating from the school in 1983 and stayed through the 1995 season.
Dan Algeo, who previously served as O'Hara's athletic director, was one of Jim and Mickey Algeo's nine children.
Mr. Algeo is survived by his daughter, Becca. Viewings were scheduled for 6 to 9 p.m. Tuesday and 9 to 11 a.m. Wednesday at St. Stanislaus Church, 51 Lansdale Ave., Lansdale, Pa. 19446.
A funeral Mass will follow at 11 a.m.
Inquirer staff writer Joe Juliano contributed to this article.