Rattay relieved Gradkowski at Chicago on Sunday and rallied the Bucs to a late-game tie with the Bears. The Bucs subsequently lost in overtime 34-31, but Rattay had a strong outing off the bench, competing 20 of 35 passes for 268 yards with three touchdown passes and one interception.
"It's just the correct move for us at this point," Gruden said. "I believe that [Rattay] gives us the best chance to win right now."
A sixth-round draft choice from Toledo, Gradkowski has started since Chris Simms was injured in a Sept. 24 game against Carolina and had his spleen removed only a few hours after the contest. Gradkowski is 3-8 as the starter and has completed 177 of 328 passes for 1,661 yards with nine touchdown passes, nine interceptions and a quarterback rating of 65.9.
Early in his starting tenure, Gradkowski demonstrated not only remarkable poise but excellent protection of the football. In recent weeks, as opposition defenses have discerned that Gradkowski lacks deep arm strength, his errors have increased.
Gradkowski has thrown more interceptions and his judgments have been increasingly questioned.
The quarterback question will be huge for the Bucs entering the coming offseason. Simms is eligible for unrestricted free agency and, even though his playing time this year was limited because of his injury, he figures to attract a healthy market. Tampa Bay has made a contract offer to Simms, believed to be for two years, but it is not believed an agreement is imminent.
Most observers feel Simms could benefit by a change of scenery and that he will at least sample the free-agency market in the spring.
Rattay, 29, was a seventh-round pick of the San Francisco 49ers in the 2000 draft. The former Louisiana Tech standout was acquired by the Bucs in a 2005 trade for a low-round draft choice. He has appeared in 34 games with 16 starts and has completed 385 of 634 passes for 4,292 yards with 27 touchdown passes and 19 interceptions for a career passer rating of 82.6.
In 2004, Rattay started nine games for the 49ers. He logged for starts for the Bucs last season but has played in only two games this year.
Len Pasquarelli is a senior NFL writer for ESPN.com.