Some teams carry three quarterbacks into the regular season as a means of providing themselves insurance in case their lead signal caller goes down. The worst thing that can happen to a team is for their starter to go down early and have a backup quarterback in with no net to catch the offense if he were to fall.
The Buccaneers currently have four quarterbacks on the roster as the league prepares to enter pre-season. While conventional wisdom says to keep three quarterbacks on the active roster, there have been teams who drew their stock down to just two in the name of providing greater depth at other positions on the field.