PITTSBURGH -- Mildred Harrison had hoped her son, James Harrison, was finally ready to stop playing football. She's prepared to resort to crying this offseason to get the 38-year-old and former NFL Defensive Player of the Year winner to officially retire after the 2016 season. She's kidding -- sort of. She's heard too many stories of Harrison's teammates crawling out of bed each morning.

But after Harrison's five sacks in the past five games, Mildred is getting signals that James will go until he's 40. She's not thrilled, but she understands, because of the familial fire churning inside her "baby" as he leads the Pittsburgh Steelers defense into Sunday's matchup with the Buffalo Bills.

"Now that his father's gone, he wants to do what makes his father happy," Mildred said.

James Harrison Sr., who died of lung cancer in May at age 76, loved to stand outside the family-and-friends suite at Harrison's games and tell stories of his son to anyone who would listen. After breaking Jason Gildon's franchise sack record in Week 11 at Cleveland, an hour from his hometown of Akron, Harrison told reporters after the game, "I was thinking about my father, how he's not here for it."

The ageless James Harrison is as hard to block as ever, as he's picked up his play late in the season. Mark Alberti/Icon Sportswire

Harrison, who declined a recent request to speak about his father's impact on his life, was by his father's side as he grew ill. Harrison Sr. -- a former Golden Gloves boxer in the military -- was his favorite fishing buddy and always supported his football plans growing up.

Harrison Sr. died peacefully, and Mildred believes her son takes a peaceful approach to his 14th NFL season by savoring moments. He used to hole up in his home after losses but takes them better now.

"He's thinking a lot about his father throughout this," she said. "He loves the game until it becomes too hard to compete."

If dad's spirit hasn't left him, neither has the raw pass-rush ability, spawning a late-late-career surge for the Steelers' December playoff push.

The man released three years ago was all but retired before re-signing with Pittsburgh out of injury necessity in 2014. That he has re-emerged as arguably the team's best pass rusher, playing more snaps than former first-round picks Bud Dupree and Jarvis Jones, surprises no coach who has seen him play over the past decade.

"He whipped Father Time," said Buffalo Bills coach Rex Ryan, who watched Harrison up close as the former Baltimore Ravens defensive coordinator.

Harrison still keeps in touch with friend and former coordinator Dick LeBeau, who said not many can "mash the pocket" with Harrison's strength, regardless of age.

LeBeau is now the coordinator for the Tennessee Titans, with whom Harrison almost signed as a free agent in 2015. Harrison stayed with Pittsburgh for two years and nearly $3 million, and he might be working on another contract. The Steelers increased his workload nearly a month ago, and he played 45 snaps last week against the New York Giants.

"An immovable object -- he's still that," LeBeau said. "He's so strong, and generally players lose a little bit of a speed factor. But when you have the strength like him, you don't have to be as fast."

In the offseason, Harrison trained in Phoenix to ensure his body could take the rigors of another NFL season. Upon return, coach Mike Tomlin got the Harrison he expected: A player who sizes up matchups with opposing tackles and plays to his strengths. And his energy has permeated the locker room, from weightlifting to locker-room chatter.

Why all the questions @jhharrison92 ?? A video posted by Maurkice Pouncey (@maurkicepouncey) on Dec 6, 2016 at 7:49am PST

Harrison might not lead in the traditional sense, Tomlin said, but his example is enough.

"He loves every aspect of this," Tomlin said. "A lot is written about his strength or things relative to his strength, but I just think the guys gravitate toward him because he’s a fun guy to be around."

Before the sacks this season, Harrison publicly sparred with the NFL over an investigation into Al-Jazeera America's report that Harrison and others used performance-enhancing drugs (the NFL cleared Harrison). He uses social media to point out the NFL's diligence in drug-testing him.

While Harrison can worry about honoring his father on the field, perhaps his mother can handle the NFL.

"Tell Goodell to leave my son alone," Mildred said. "He doesn't want to answer to me."