SANTA CLARA — Alex Smith always considered the boos from his home crowd just part of the territory as an NFL quarterback.
He'd rather hear something than nothing at all to know they truly care.
For those numerous unfriendly jabs and the constant criticism he has endured in a roller coaster seven-year career, Smith is suddenly giving people plenty to cheer about this season for surprising San Francisco (3-1).
"You can't be sensitive," Smith said Wednesday. "I think it's tough to play quarterback in the NFL if you don't (have a thick skin). That's anywhere. You're going to face scrutiny. That's the way it is."
The 2005 No. 1 overall draft pick is thriving under new coach Jim Harbaugh's guidance and in his multilayered West Coast offense, rallying the 49ers from a 20-point third-quarter deficit to an improbable 24-23 win at Philadelphia on Sunday. Smith hopes to continue that progress through a tough home test Sunday against Tampa Bay, which is also 3-1 and whipped the Niners 21-0 last November at Candlestick Park.
Against the Eagles, Smith went 21 of 33 for 291 yards and two touchdowns without an interception. In the second-half comeback, he completed 13 of 17 for 201 yards and TDs to Joshua Morgan and Vernon Davis.
Davis, running back Frank Gore and other key members of the offense have stuck by Smith through all the ups and downs, the promotions and demotions, along the way.
"It's Alex's first time having someone who really can understand him and show him the quarterback position and put him in great situations," Gore said. "Coach Harbaugh is doing a great job with him. Alex is balling."
Smith has only two interceptions in his last 259 attempts since throwing a pick on his final pass in a 27-24 loss to the Eagles last Oct. 10. What a difference from his performance this past Sunday.
For the first time in Smith's career, he has more touchdown passes than interceptions — 55-54. He began his rookie season with 11 picks before completing his first TD pass.
At age 27, he is exhibiting the poise under pressure and heads-up decision-making Harbaugh believed Smith still had in him when the former NFL quarterback took over as the new Niners coach earlier this year.
Harbaugh quickly put his faith in Smith, handing over the playbook to the QB this spring well before he re-signed as a free agent once the lockout lifted.
"He has always struck me as a very confident guy," Harbaugh said. "Very tough guy, very mentally tough guy, very physically tough guy. He's been easy to coach, he really has. Extremely bright, book smart and football experienced. It's been easy coaching him. He's done it all."
Smith was the favorite all along to win the starting job over rookie second-round pick Colin Kaepernick. Even if he was about a week behind after getting his new deal because of the post-lockout rules for when newly signed players could practice.
For Smith, the explanation for his strides is fairly simple: just as basic as staying within himself.