The Ravens released a statement about the move:
Williams started at nose tackle for the first five games of the season. He's recorded 15 total tackles and no sacks, and his Pro Football Focus grad stands at a lackluster 58.9.
Despite his placement on the reserve list, the Ravens are still set to travel for Sunday's Week 6 road game against the Philadelphia Eagles at Lincoln Financial Field, per Jeff Zrebiec of The Athletic.
Although the NFL hasn't dealt with a second widespread outbreak similar to that of the Tennessee Titans, who recorded 24 positive tests in a two-week span beginning in late September, there's been an uptick around the league in recent days.
Five teams have placed at least one player on the reserve/COVID-19 list since Friday, per ESPN's Field Yates.
The league has been willing to play through isolated positive tests as long as contact tracing measures are taken and the team otherwise produces negative tests leading up to the game, but other contests have been postponed over the past two weeks because of multiple positives.
It's a troublesome trend after the first three weeks were played largely without issue. It could become more problematic if the positive tests continue, as teams have been forced to use their bye weeks early to accommodate schedule changes, leaving less flexibility for the remainder of the campaign.
If the Ravens' game against the Eagles moves forward, Justin Ellis will likely draw the start at nose tackle. The team doesn't have another tackle on the roster or practice squad, so it would go with a three-end line if Ellis went down, barring a late-week signing.
Baltimore is scheduled to have a bye in Week 7, giving Williams an extra week before a potential return Nov. 1 against the Pittsburgh Steelers.