Jameis Winston just wants to do great things. Tampa Bay’s quarterback threw five interceptions and lost a fumble in his team’s 37-26 loss to Carolina in London, and now has an N.F.L.-high 86 turnovers over the five seasons since he was the No. 1 pick in the 2015 draft. In trying to explain his frequent mistakes, he said they are a matter of ambition. “Sometimes I do want to do great things,” Winston told reporters. “But you can do great things but protect the team at the same time.” The Panthers, meanwhile, improved to 4-0 since shutting down the injured Cam Newton (also a No. 1 pick) in favor of Kyle Allen, a second-year player who was not drafted.