LANDOVER, Md. -- Moments after the Tampa Bay Buccaneers fell to the Washington Football Team 29-19 on the road Sunday, coach Bruce Arians said his team -- now 6-3 after two straight losses -- has some "soul-searching to do," and he chided it for penalties and mental errors that continue to be costly.

"It's very disappointing," Arians said. "It's very alarming to watch the energy at every practice and show up with a lack of execution and energy that it takes to win on Sunday. We've got a lot of soul-searching to do."

Against the league's worst pass defense -- a team the Bucs were favored to beat by 10 points and that would lose its star defensive player Chase Young midway through the second quarter -- quarterback Tom Brady completed only three passes of more than 20 yards and was intercepted twice.

The Bucs surrendered 256 passing yards and a touchdown to Washington quarterback Taylor Heinicke, with Antonio Gibson rushing for two more against the league's top-rated run defense. The defense allowed Washington to orchestrate a 19-play touchdown drive that ended all hope of a comeback.

Self-inflicted wounds -- particularly penalties -- have been the Buccaneers' Achilles' heel all year. After an 11-penalty loss at the New Orleans Saints two weeks ago, Arians called on the team's leaders to hold each other accountable, but that hasn't stopped the errors. The Bucs also had a three drops, making it 15 for the year, according to ESPN Stats & Information research.

"Energy and passion are very fixable," Arians said. "The penalties -- they've gotta get corrected sooner or later. The first play of the game -- they're shifting and we jump offsides. They don't even run a play and we jump offsides. The stupidity has to go away if we're gonna go anywhere."

Tight end O.J. Howard jumped offside on the very first snap when Washington shifted. A neutral-zone infraction on defensive end William Gholston advanced Washington 5 yards forward just before halftime. A false start on right tackle Tristan Wirfs pushed the Bucs back 5 yards just before halftime.

In the third quarter, a defensive pass interference call on Dee Delaney took Washington from the Tampa Bay 14 to the 1-yard line before a TD by Gibson made it 23-13.

"It has nothing to do with ability. It's about execution and being a smart football team. We're a very dumb football team. And that's a reflection on the coaches," Arians said.

"We came out there flat-footed for whatever reason," inside linebacker Devin White said. "Everybody wasn't on the same page. Everybody didn't have the same amount of energy. And that's something we preached all week." He added: "We had a great week of preparation, but it don't mean nothing if we don't execute on Sunday."

As for Brady, it was just the third time in his career that he threw two interceptions in the first half. The first one bounced out of the hands of rookie wide receiver Jaelon Darden. The second came when he overthrew Mike Evans on a slant route, and it wound up in safety Bobby McCain's hands.

"It has nothing to do with the receivers. It was him," Arians said of Brady, who suffered the second-largest road upset in his career and just his second back-to-back defeats as a Buccaneer.

Visibly upset, Brady spoke to the media for only 1 minute, 43 seconds after the loss.

"We just never really played on our terms. We played behind the whole game. They played a good game. They had a good plan," Brady said. "It doesn't matter who you play if you have a bunch of self-inflicted errors too. We've gotta go out and execute the plays that were there."

When asked about his two interceptions, Brady said, "We started with the ball. They came away with it so ...."