HOUSTON — He wasn’t the second coming of Joe Montana, obviously. Not ever.
But maybe Alex Smith can pull off something almost as remarkable after his long NFL hibernation.

Can he be the successful second coming of . . . Alex Smith?
What a tale that would be. It won’t happen overnight. But one essential part of the Smith resurrection story took place in a blink:
With the 49ers trailing 21-0 Sunday in a game they would go on to lose 24-21, coach Mike Singletary decided to sit Shaun Hill and put in Smith to start the second half.
Just like that, the 49ers’ universe changed.
It was a surprise to Smith “” “I wasn’t sure, I guess I was ready for anything,” he said later.
A surprise to his offensive teammates, many of whom didn’t know the switch had occurred until Smith showed up in the huddle.
A surprise to practically everybody in the NFL, where it has been assumed Singletary was reasonably committed to Hill.
“I just felt it was time to make the switch,” Singletary said later. “No long, drawn-out thought process. Just, hey, you know what? Let’s make the change.”
Singletary also said he doesn’t know which quarterback will start Sunday in Indianapolis, but there should be no mystery, and Singletary had to know it.
When you make a quarterback change and your season is on the line and the new guy is better than the former guy, you stay with the new guy. Who happens to be the former guy twice removed, but, oh, well.
It will be Smith, who has the stronger arm, fresher legs and much greater capacity to get the ball downfield to the 49ers’ weapons.
It won’t be Hill, who was flummoxed in the 49ers’ previous loss to Atlanta and who struggled again in Sunday’s first half as the offense stalled.
The 49ers’ record fell to 3-3, quite a comedown from the roar of their 3-1 start. They need someone to convince them, once again, that they’re good.
That would be Smith. Amazingly, he is their best hope.
“You know, we’ve got playmakers on the field,” Singletary said. “If we can get the ball to them, we’ve got a chance to do some good things.”
On his first pass Sunday, Smith fired a 17-yard completion to Michael Crabtree (key new weapon). Bingo.
Smith went on to hit on his next five passes, looked calm in the pocket and generally made every 49ers fan wonder where the heck that had been in the previous four seasons.
Smith threw a touchdown pass to Vernon Davis. Then another. Then a third (tying Smith’s career-high for touchdown passes in a game), while hooking up nicely with Crabtree a few more times along the way.
All with his heart beating wildly.
“I’d be lying to you if I said it wasn’t,” Smith said. “Just because it had been a while since I really took some game snaps. So, no question, it’s nice to get in there and finally get sweating and not thinking about it anymore.”
This wasn’t the same antsy guy who was awful as a rookie, decent but fragile in Year 2, bad and then hurt in 2007, lost in 2008 and not terrific in the training-camp battle with Hill this year.
Smith hadn’t played a down since Nov. 12, 2007, but he didn’t look rusty. It might have been only a temporary flash, but this was Smith the way he was supposed to be “” and the way the 49ers’ offense was supposed to be “” from the moment he was chosen No. 1 overall in 2005.
At the end, Smith couldn’t convert the 49ers’ final drive “” his fourth-down pass was short of Isaac Bruce and was intercepted by Eugene Wilson “” and the Texans held on.
But he gave them a shot. Smith was the igniter.
Stat line: Smith completed 15 of 22 passes for 206 yards, with three touchdowns and one interception, for a 118.6 passer rating.
“It’s a longtime coming,” receiver Arnaz Battle said of Smith. “He’s gone through a lot.”
Yes, he has, and yet Smith still is only 25. He is the favorite of general manager Scot McCloughan and he has a better chance of enlivening this offense than any other 49er.
Naturally, Singletary said he needed to look at the film when asked if he thought Hill played poorly. But every smoke signal points to Smith at quarterback, for at least a few weeks, just to see how long this lasts.
“I don’t like going back and forth,” Singletary said.
Alex Smith is back. More than four years after he joined this franchise, he’s back, precisely when they need him most.