David Ahern, 28, Babson College’s first baseball All-American – The Boston Globe

While he lay in a coma at Tufts Medical Center, Blue Sox players presented a team-autographed game ball to his family, along with Mr. Ahern’s uniform No. 41, which his brother Michael wore during the first and third games of the team’s final playoff series. During the second game, the team displayed the uniform in the dugout.

The baseball remained at Mr. Ahern’s bedside, and at times his family placed the jersey on him during a vigil that ended Sunday when he died at 28, having never regained consciousness. The family is awaiting tests to determine the cause of death.

“During the last weeks of the regular season and the first two rounds of the playoffs, Dave was the teammate who picked us up by the way he played and with his unique positive manner,” said Ross Curley, a Lexington teammate who took part in the hospital presentation.

Mr. Ahern batted .467 in seven games of the first two playoff rounds, and he was a defensive force in the outfield and at first base for the Blue Sox, an amateur summer league team.

Team manager Rick DeAngelis said the championship rings will be themed to memorialize Mr. Ahern and that his jersey will be retired and displayed at all future home games.

Even though the team won the title in 2015, Mr. Ahern felt his performance was not up to his standards. After some reflection, he rejoined the Blue Sox late in the 2016 regular season.

“Dave was just immense down the stretch. During the first two rounds of the playoffs he spoke up about what it takes to be a winner and then carried us,” said DeAngelis, whose players wore No. 41 T-shirts under their uniforms and displayed Mr. Ahern’s initials on their caps during their series sweep. “He was a huge reason we were champions.”

Mr. Ahern graduated in 2006 from Bedford High School, where he was a Dual County League All-Star in hockey and baseball. A pitcher and outfielder, he had Tommy John elbow surgery after his sophomore season at Babson, and his recovery was on target until a lung infection sidelined him the entire 2009 season.

“I was hoping to play both sports at Babson,” he told the Globe in 2010, “but the injuries and the illness pretty much made the decision for me just to stay with baseball.”

His extra season of college eligibility as a fifth-year senior was one of the greatest in program history. In addition to his Division 3 All-America selection, he was named Babson’s male athlete of the senior class of 2011 and the New England Women’s and Men’s Athletic Conference Player of the Year. He hit .438, was 5-2 on the mound with a 1.19 earned run average, and broke or tied nine school records.

Mr. Ahern, who graduated with a bachelor’s degree in business marketing, was a sales manager at ZeroTurnaround, a Boston software firm. In the summer of 2011, he played professionally in the independent Can-Am League with the New York Federals.

“He was a leader and in so many ways larger than life — an unbelievable teammate in every way,” Babson head coach Matt Noone said. “Dave was by far one of the toughest kids I ever coached, yet the kindest person one would ever meet.”

David M. Ahern and his brothers Michael of Boston and Joe of Los Angeles were coached in the North Medford Little League by their father, Joseph. The family moved to Bedford in 1995.

“People just loved being around him because Dave made everyone feel welcome and because they knew he was there for them,” his brother Joe said.

Mr. Ahern’s concern for others was evident during a stint in 2010 with the Sanford Mainers of the New England Collegiate Baseball League. One of his biggest fans that summer was a disabled boy, and Mr. Ahern signed autographs for the youngster and spent time with him because “he had a heart of gold,” Joe said.

At Bedford High, where Mr. Ahern also received an award for his talent as a sculptor, he encouraged his classmate Sam Grainger to try out for the hockey team as a goalie. They became baseball and hockey teammates and remained close friends. “As an athlete and a friend, he was the kind of person that you would look up to and think, ‘What’s Dave going to do? We need him,’ ” Grainger said.

In addition to his father and brothers, Mr. Ahern leaves his mother, Denise (Cajolet) of Bedford; his sister, Rachael of Somerville; his paternal grandmother, Irene (Delaney) of Medford; his maternal grandmother, Alice (Healey) Cajolet of Cambridge; and his girlfriend, Mia Morgan of Bedford, N.H.

A funeral Mass will be said at 11:30 a.m. Saturday in St. Agnes Church in Arlington.

“Dave was our rock, the guy our team looked to for strength,” Noone said. “Words cannot describe the sadness and pain I feel. The only thing I can do is take solace in the fact I knew him and had the great honor of being part of his life.”