Voluntary football workouts have been suspended.
Williams is the top-rated quarterback in the class of 2021.
Maryland tested 105 student-athletes in its original screening.
Griffin was the team's leading goal scorer and preseason Big Ten Player of the Year in 2020.
Baker replaces Cory Robinson, who left the program in March.
Tyler Blohm and Elliot Zoellner hope to come back strong after a shortened season.
The three-star product joins the Terps from nearby St. John's College High School.
Chol Marial and Donta Scott are the Terps' only frontcourt options for next season.
Jones was an All-Big Ten honorable mention in his lone season in College Park.