Tennessee's next head coach likely won't have all of last year's best players at his disposal.
To'oto'o led the Volunteers with 140 tackles through 22 games across his two seasons.
Gray topped Tennessee in scrimmage plays (187), total yards (1,026), and touchdowns (six) through nine games last year. He's rushed for 1,311 yards and eight touchdowns while catching 43 passes for 369 yards and three scores since 2019.
Crouch ranked third on the team in tackles in 2020, while Johnson started five games.
The players' decisions come just days after Tennessee fired head coach Jeremy Pruitt on Monday. Pruitt committed multiple recruiting violations and was assessed under fire-for-cause provisions.
Tennessee also parted ways with multiple assistants, including outside linebackers coach Shelton Felton and inside linebackers coach Brian Niedermeyer.
The school had already lost two quarterbacks to the transfer portal recently, as Jarrett Guarantano and JT Shrout joined Washington State and Colorado, respectively.
The Volunteers finished 3-7 last season and have posted just one winning campaign since 2017.