Eric Baylor, 23, allegedly argued with Williams and then they got into a fight.
However, the sheriff's spokesman said that police have questions about Williams' version of events.
"His account is that they were horsing around in the kitchen and he fell on the knife that his brother was holding," sheriff's spokesperson Cristal Bermudez Nunez said. "They expained that Williams and Baylor were arguing and that is what led up to the stabbing."
Williams has been released from the hospital.
"Based on what Michael Williams says happened, and where it occurred in the home, that doesn't match up with the evidence we found at the scene," Bermudez Nunez said.
Williams is the victim in this case. He faces trespassing and criminal mischief charges.
"We are aware of the situation that occurred at the residence of Mike Williams and are working with him and the authorities to get additional information," the Buccaneers said in a statement. "While we have limited knowledge at this time, our primary concern is for the safety and well-being of all involved. We will refrain from further comment until we can get a better understanding of the situation.''
In February, new Buccaneers coach Lovie Smith said: "There's a pattern here, and it's disturbing. No one is bigger than this football team. He has to understand that. Have I been disappointed in Mike Williams? Of course. There's a standard. We're just not going to put up with it, no matter who it is. You have to be good on the field and off the field -- simple as that. If you're not doing what you need to do, one or the other, you have problems, and that's where Mike has to take care of a few things."
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Aaron Wilson covers the Ravens for The Baltimore Sun