Quinn and Krenzel struggled to 91 combined passing yards and the rest of the team proved even worse than helpless.
"We hurt ourselves a lot today with penalties," said Quinn, who was benched at halftime in favor of Krenzel after guiding the offense to four punts.
The Bears have had worse days this year drawing flags than in Sunday's 10-penalty, 78-yard effort, but it's hard to find any penalties all year as costly as the one on the Bears' very first play from scrimmage against the Bucs.
It set a tone of incompetence on the way to their 1-5 record.
With Quinn badly in need of a confidence infusion after two poor starts as Rex Grossman's replacement, the Bears got a dream play on their first snap. Thomas Jones caught a short pass in the flat to the right from Quinn and broke it 77 yards for a touchdown.
However, David Terrell's unnecessary offensive pass interference on the opposite side of the field negated the touchdown. From there, the Bears' offense struggled all day to 167 net yards, 11 first downs and a23 percent third-down conversion rate (3-of-13).
"The first play, it started right off the back," said Quinn, who completed 5-of-9 for 47 yards. "We had a big play and the call was away from the side of the play and that was kind of how the day went.
"We had a lot of situations where it was first-and-long because of penalties. We kept getting good plays called back and that's something we have to work on."
An unsportsmanlike conduct penalty for taunting the Bucs against Bears safety Mike Green pushed the offense out of needed field position in the third quarter and false starts by Qasim Mitchell in the first quarter, John Tait in the second quarter and Ruben Brown in the third quarter helped kill drives.
Cornerback R.W. McQuarters contributed a pass interference in the third quarter, negating his own interception.
"We had penalties and missed blocks and we had sacks," Bears center Olin Kreutz said.
Even with their clownish behavior, the Bears found a way to make the game closer, albeit not much more interesting.
The Bears' defense allowed its two longest scoring drives of the season in the first half. Martin Gramatica's 22-yard field goal capped a 93-yard, 10-play second-quarter drive and Michael Clayton's 6-yard TD pass from Brian Griese ended a 16-play, 93-yard epic. Gramatica had also kicked a 22-yard field goal with 12:23 left in the third quarter before the Bears' defense struck back.
But Brian Urlacher then stripped running back Michael Pittman of the ball and safety Todd Johnson recovered at the Bucs' 31. Krenzel then threw a 13-yard pass to tight end Desmond Clark and running back Thomas Jones accounted for the other 18 yards on five carries, including a 1-yard TD run with 3:51 left in the quarter to pull the Bears back within 13-7.
"I did some good things," said Krenzel, who went 9-of-19 for 69 yards. "There's some things I would have liked to have done differently."
One of those came at the start of the fourth quarter with the Bears facing second-and-six at their 26. The rookie out of Ohio State flinched in the face of a blitz, threw too quickly and just high enough for fullback Bryan Johnson to get his hand on the ball without catching it.
The deflection wound up in the hands of Bucs cornerback Ronde Barber for an interception that was returned to the Bear's 11. Three plays later, Pittman scored on a 3-yard run on third-and-two and the offensively-challenged Bears were down 19-7 with 8:52 left.
Essentially, they were beaten.
"That was the turning point in the game, and from there we were trying to play catch-up," Krenzel said.
In the third quarter they had squandered on excellent shot at the lead when linebacker Hunter Hillenmeyer stripped Bucs back Mike Alstott of the ball and safety Mike Green recovered at the Bucs' 24. The Bears were 24 yards from the lead then.
But officials called Green for taunting, pushing the Bears back out of scoring range. They failed to gain a first down and punted.
"They said it was an excessive celebration," Hillenmeyer said. "I don't even think they gave a (player's) number. It didn't look like we were celebrating all that much.
"But I think you shouldn't be discouraging players from being enthusiastic about the game."
Added Green: "I didn't do anything except wave and say just 'our ball,' and showed them I had it.' "
For the third straight game the Bears allowed a 100-yard rusher -- Pittman gained 109 yards on 23 carries – and Brian Griese was efficient enough to sustain a 32:11-27:49 ball control edge for the Bucs (2-5).
It all added up to more Bears misery as they try now to decide who starts Sunday night at quarterback in Chicago against the San Francisco 49ers and whether they should add a fourth quarterback in Tim Couch.
"A lot of people hurt us for the second week in a row," coach Lovie Smith said.
A lot of people hurt them for the fourth week in a row.