Niners head coach Jim Tomsula got a good look at the pass that got AJ McCarron going, a 37-yarder to A.J. Green.

SANTA CLARA, Calif. - AJ McCarron and Andy Dalton were cracking jokes to keep loose Sunday during McCarron's first NFL start and in the end the joke was on conventional wisdom.

The Bengals couldn't run a lick on the road and gave their quarterback a bunch of thorny third-down situations. But the defense gift-wrapped his first win, a gutty 24-14 job over a 4-10 team that personifies McCarron's gritty

intangibles. Both the Bengals and McCarron found a way to secure that fifth straight postseason despite a season-low 242 yards of offense

 "We slacked as an offense, but the positive thing is we took care of the football for the most part," McCarron said. "They had turnovers, we didn't, and that's the key to the game. I felt good about it."

And why not? Sure his longest touchdown drive was 36 yards and he handed off on one of them. But he also made the two throws of the game, a quick dart to wide receiver Marvin Jones on third-and-one from the 49ers 8 when it was still 7-0. And then on the very next drive, a one-play affair, he rifled a 20-yard pass down the seam for rookie tight end Tyler Kroft's first NFL touchdown pass. That made it 21-0 with 53 seconds left in the first half and that was it.

"I thought he played well," Jones said. "Especially in the first half when we were throwing the ball and he was really getting into the flow. He didn't make any mistakes. He's confident. All the qualities that were said about him during the week, that's what he showed."

McCarron responded as advertised. With a combination of 'Bama heat and Orange Beach cool. He played like he'd been there before with a 115 passer rating culled from one touchdown pass on 15 of 21 for 192 yards. Even his defensive mates noticed.

"AJ has the most confidence in the world," said WILL backer Vontaze Burfict "This whole week he's been carrying his shoulders up high not feeling like second string. He showed that today. He showed new confidence . . . I think he took some sacks and it was better to take a sack than throwing picks."

That was the idea. He didn't throw any picks. The only turnover was running back Jeremy Hill's fumble. Once McCarron threw a 47-yard bomb to Jones to set up Mike Nugent's 22-yard field goal to make it 24-0 halfway through the third quarter, McCarron got sacked or threw a pass just seven times the rest of the way.

"We have a 24-0 lead so our mindset kind of changes as an offense," McCarron said.  "Whatever I do, I'm not going to turn it over. There's no reason to take chances. You have to know when to take chances and when not to."

Suffice to say offensive coordinator Hue Jackson has done his work well and drilled into McCarron the evils of turnovers. Even though he threw it just 12 times while the backs ran it 18 times in the first half, he didn't think it was a conservative game plan.

But in a game he played all four quarters, Dalton has never thrown fewer than 21 passes. He has hit 22 twice, most recently in last year's win in New Orleans.

The Niners, McCarron said, didn't start crowding the run until the second half. Before then, the Bengals went after what McCarron called a two shell with coverage tilted to wide receiver A.J. Green.

So that explains coming up with the big throws to Jones and Kroft late in the first half. Although the 37-yard bomb to Green on the second drive admittedly got McCarron going.

"Marv did an excellent job by not pushing too far and popping right there," McCarron said of the third-and-one throw that was wide open. "We've never made that throw but I saw the corner drop off."

 The TD to Kroft was out of that ilk in that McCarron took what was there in the wide open middle against the blitz.

"The back-side safety didn't get over enough and Tyler did an excellent job getting out quick to catch the ball and get in the end zone," McCarron said.

McCarron called it "a good day," and it was. You don't make the playoffs every day. But while left tackle Andrew Whitworth saluted McCarron for doing his homework, he also allowed, "It wasn't good enough. Today it was. But we have to play better as an offense."

Whitworth said after the Browns ran over the 49ers last week and dropped them to next-to-last in the league rush rankings, the Niners adjusted their run defense and gave the Bengals a look they hadn't seen.

"Something they haven't really been doing," Whitworth said." That's why the guys over there get coordinators and players get paid too. They made a good adjustment that hurt us a bit. They had a lot to prove. The week after you get torched like that on the road, you are going to come home and you are going to fight your butt off. They had that attitude today."

 The final line was 68 yards on 36 carries. But all they needed were those two McCarron throws.

"He is a guy that is prepared and paying attention," Whitworth said. "He has a guy in Andy who is a guy who is always prepared and understands things really well. He can teach him and be in the room with him and to look up to him. We weren't really worried about him being prepared.  We knew he would come in and know exactly what we needed to do and understand the plays and formations."

 It was ugly, but was it really? Just like their quarterback, taking a sack or running out of bounds, the Bengals lived to fight another day.

"I felt like I took what they gave me and if it was there, we hit it, and lived for another down," McCarron said. "I didn't see any balls where I should have thrown that or tried to fit it in there. I felt good about my progression and my reads and took what they gave me."