PHILADELPHIA — After spending last season with the Los Angeles Lakers and the first few weeks of this season out of work, Wesley Matthews returned to the Milwaukee Bucks in early December. The day after he signed his new contract, he found himself coming off the bench for the team in a lopsided win over the Miami Heat.

“Which was fine for me,” he said in an interview this week. “I like jumping into the fire.”

Matthews was familiar with the Bucks and their system, having played for the team two seasons ago. But at this stage of his career, he seems more than willing to take on whatever responsibilities are asked of him. He rattled through the list: “Coming off the bench, starting, playing 20 minutes, playing 15 minutes, playing 30 minutes.”

And for a player who grew up in Wisconsin and starred at Marquette, helping the Bucks repeat as N.B.A. champions would be a career-defining moment.

“That would be a really great story, to put him in a position to achieve such a monumental goal,” the Bucks’ Pat Connaughton said.

Make no mistake, contenders need players like Matthews: defense-minded veterans who ply their trade in the shadows. It should be noted that Giannis Antetokounmpo casts a particularly long shadow, and he was at his all-world best for the Bucks in their 118-116 win over the 76ers on Tuesday night, finishing with 40 points, 14 rebounds, 6 assists and 3 blocks, none more important than his game-saving swat of Joel Embiid’s layup attempt in the closing seconds.

Matthews, on the other hand, assembled a smorgasbord of small delights. The Bucks were trailing by 10 when Matthews fought for an offensive rebound on the opening possession of the second half, the ball eventually finding its way to Brook Lopez for a layup and a 3-point play. A few minutes later, Matthews knocked down a 3-pointer.

In the fourth quarter, with Milwaukee’s comeback in full swing, Matthews met the 76ers’ James Harden at the scorer’s table so that he could help defend him for the game’s final 6 minutes 46 seconds. Matthews finished with 5 points, three rebounds and an inordinate number of hustle plays.

“We talk about trying to make everything difficult, to make everybody earn everything they get on us,” Bucks Coach Mike Budenholzer said, “and he embodies that.”

Not that he views his career this way, but Matthews has had brutal timing. When he was with the Bucks two seasons ago, the Lakers won it all. When Matthews joined the Lakers last season, they were undone by injuries and lost to the Phoenix Suns in the first round of the playoffs — while the Bucks won their first championship in 50 years.

“I wanted them to win,” Matthews said. “Phoenix beat us, so I definitely didn’t want them to win, even though I’ve got friends over there. But yeah, I was happy for these guys, I was happy for the city, and I was happy for the state and the organization. Everybody’s good people.”

Matthews, 35, coped with uncertainty at the start of the season, which began without him. He worked out by himself at home and kept in periodic contact with Jon Horst, the Bucks’ general manager, along with a few other teams. Matthews was fairly confident that his career was not finished — not yet, anyway.

“You obviously don’t know anything for certain, but I had a good feeling,” he said. “It was just going to be a test of how badly I wanted it.”

In some ways, he was accustomed to the grind. Back in 2009, he started his N.B.A. career the hard way — by going undrafted. He subsequently signed a nonguaranteed deal with the Utah Jazz, then spent his first couple of months with the team living out of a hotel. He later upgraded to a small apartment with a month-to-month lease. He has since earned more than $100 million over 13 seasons with seven teams.

“He brings that energy, that tenacity, that camaraderie — a little bit of everything,” Connaughton said. “I think the ability to have an impact on the game, without necessarily scoring and without necessarily doing it with statistics, is super impressive. It’s something I’ve always admired.”

The Bucks were 23 games into their season when Matthews officially joined them on Dec. 3.

Training camp? Forget it. Matthews had not even practiced when he took the court against the Heat.

“I mean, you’re in the best shape you can be without playing in the N.B.A.,” he said. “I was working every day, staying ready for this moment, for this opportunity.”

On Tuesday, Matthews was in the starting lineup so that he could match up with Harden for stretches — no small task. It was the first time the Bucks had faced the 76ers with Harden on their roster. Like many teams around the league, the 76ers are still figuring things out as they head toward the playoffs. The Bucks and the Nets entered the game with identical 46-28 records, part of an enormous logjam near the top of the Eastern Conference.

“We just need to get better continuity,” Doc Rivers, the coach of the 76ers, said before the game. “We haven’t been together long.”

In fact, Rivers said he thought that there were only two teams that were fully prepared for the playoffs: the Bucks and the Suns, who faced each other in last season’s N.B.A. finals.

“Those two teams know exactly who they are, and they know exactly what to do,” Rivers said. “They’ve been through the fire.”

Back with the Bucks, Matthews has made it look as if he never left: defending, rebounding, energizing, winning.