The Big Ten halted play Tuesday, but it left open the possibility of conducting a spring season.
Tagovailoa transferred from Alabama in May.
The group seeks to diversify the collegiate and professional coaching ranks.
He previously committed to LSU in December.
Penn announced he would play at LSU.
Williams is the top-rated quarterback in the class of 2021.
Baker replaces Cory Robinson, who left the program in March.
The three-star product joins the Terps from nearby St. John's College High School.