Fans have called for the head coach to be fired after leading the team to seven consecutive losses this season.
Speaking at a press conference, Sheridan said: "It definitely is not warranted, and it may be hard for people on the outside who don't know Greg because of some of the criticism he apparently is receiving and I don't follow that, it definitely isn't warranted.
"I've worked for a lot of quality people in this profession, long before I ever came to the NFL and I've certainly worked for quality people in the National Football League.
"I would put Greg up against anybody I've worked for in regards to a guy of single-mindedness and purpose toward doing the job he's been asked to do and doing it with complete and total integrity. In our profession, if we get criticised for that, then he should be criticised."
The Buccaneers face the Seattle Seahawks this weekend.