Williams, who signed a six-year, $40 million contract before last season, was treated and released from a hospital for a thigh wound on Sunday.
The Hillsborough County Sheriff's Office said the fifth-year pro's younger brother, Eric Baylor, turned himself in Monday night. Baylor, 23, was held on $1,000 bond.
Bucs general manager Jason Licht said coach Lovie Smith had been in contact with Williams by telephone and that the team was still trying to determine what happened.
"The good news is Mike is healthy," Licht said Tuesday in Orlando, where he was attending the annual NFL meetings.
Deputies responded Sunday to Williams' Tampa home, finding him with a stab wound in the left thigh. The player initially told deputies the brothers were wrestling and the stabbing was accidental.
Witnesses gave statements later that the two argued before the stabbing.
Bucs co-chairman Joel Glazer, also in Orlando for the NFL meetings, said the situation "distracts from the team and the positive things we're doing" in the community.
"What this does, what any bad news does, is overshadow all the great work, all the hard work of all the other players," Glazer said. "There's 50 some-odd players doing great things. We'd rather that be the focus."
Injuries limited Williams to six games in 2013. He had 22 receptions for 216 yards and two touchdowns before spending the last nine weeks of the season on injured reserve.
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