Chester McGlockton, a four-time Pro Bowl defensive tackle with the Los Angeles/Oakland Raiders who played 12 seasons in the NFL, died early Wednesday morning. He was 42.
The announcement was made by Stanford University, where McGlockton was in his second season as a defensive assistant. The cause of death was not immediately announced.
"Everyone in the Stanford Football family is deeply saddened by the passing of Chester McGlockton," Stanford coach David Shaw said in a statement. "For the past two seasons, Chester has been a valuable member of our football staff and a wonderful friend to us all. Our thoughts and prayers go out to Chester's wife Zina and their two children."
McGlockton also spent time helping the San Francisco 49ers and former Cardinal coach Jim Harbaugh -- his former racquetball partner -- during training camp this summer as part of the Bill Walsh Minority Coaching Fellowship.
Harbaugh expressed sadness and shock upon hearing of McGlockton's death. Stanford said the school's defensive assistant died overnight.
"Chester's been a very close and dear friend over the last four years," Harbaugh said Wednesday. "It was a shock. Just sad, sad today with the news of his passing. Chester was a great guy, good man, doing the right things. ... He was helping a lot of people. We're really going to miss him. To say he was coming into his own as a coach would be understating it. He had already blossomed. He was so positive with the players and with the other coaches. He always had coaching advice or spiritual advice, a smile for you."
A native of Whiteville, N.C., McGlockton starred at Clemson before being selected 16th overall by the Los Angeles Raiders in 1992. He played 12 seasons in the NFL with the Raiders, Kansas City Chiefs, Denver Broncos and New York Jets. He made all four of his Pro Bowl appearances while with the Raiders from 1994-1997.
"I had the privilege to coach Chester with both the Raiders and the Chiefs and he was a quality person and a consummate pro -- everything you could ever want in a football player," Detroit Lions defensive coordinator Gunther Cunningham said. "I will forever cherish the opportunity to have coached him."
McGlockton's best season came in 1994, when he had a career-high 9½ sacks with three forced fumbles and 48 tackles.
"The thoughts and prayers of the Raider Nation are with the McGlockton family during this difficult time," Raiders CEO Amy Trask said.
Denver Broncos coach John Fox, who coached McGlockton when he was with the Raiders in the mid-1990s, also was stunned by the news.
"Our thoughts and prayers go out to his family," Fox said. "Chester was a great player, a Pro Bowl player. I had him while I was with the Oakland Raiders. Like I said, I'm still a little bit in shock, but he was a tremendous player. "
After his playing career, McGlockton returned to school and earned his undergraduate degree from Tennessee-Martin in 2010. He had lived in San Ramon, Calif., with his wife and two children while serving as a Stanford defensive assistant the last two seasons.
Big Chet, as he was known by many, was around 335 pounds during his career. But he had lost weight in recent years after undergoing laparoscopic weight-loss surgery and improving his workout and eating habits.
"We had done walks together, we played racquetball together quite a bit the last year, he was in very good shape for being a big man," said Steve Wisniewski, a friend and former teammate.
"I spoke to Chester yesterday, as a matter of fact," Wisniewski said. "He had a great day with his girls and was looking forward to kind of a few slow weeks as Stanford prepares for a bowl (game), so he could have some more family time. Anybody who knows Chester, he loved his wife and girls to the moon.
"Again, I just can't express how tragic it is lose someone like that at 42."
McGlockton was remembered as a fierce competitor until the end.
Harbaugh said when playing McGlockton in racquetball, he'd always remember to wear his goggles. McGlockton had attended three 49ers games this season and regularly checked in with Harbaugh and other San Francisco coaches via text message, providing words of encouragement.
"You were fighting for survival inside the racquetball court," Harbaugh said. "Just a positive, huge presence on the football team at Stanford. Dear friend, loved him."
Funeral arrangements were pending.
Information from The Associated Press contributed to this report.