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Even before he said the words, the disappointment was all over Alex Smith's face.

"Yeah, it sucks to be honest."

A day after San Francisco 49ers head coach Jim Harbaugh announced that second- year quarterback Colin Kaepernick would start Sunday's game with the NFC West- rival St. Louis Rams, Smith finally spoke on Thursday about losing his starting job despite a season-plus worth of success that some teams would kill to get from their quarterback.

Smith has always seemed to have one foot dangling off the ledge in San Francisco. Now he'll be forced to put on his corporate mask and cheer for a backup who moved up on the depth chart with success during an opportunity that came only after a head injury sidelined him for two games.

Harbaugh had said all along that he didn't subscribe to the motto that you don't lose your starting job due to injury -- funny coming from a former quarterback in this league -- but that didn't make it any less surprising for Smith.

"It stings the most because I really feel like there is something special going on here," he said. "You sacrifice and invest so much time and like I said, I really feel like I hadn't done anything besides get a concussion to really kind of facilitate this and I feel like I was playing good football."

It's no secret that Smith hasn't had the smoothest of tenures with an organization that took him first overall in the 2005 draft out of Utah.

No, Smith has never lived up to the expectations of being a No. 1 pick like certain other quarterbacks have -- unlike, say, Peyton and Eli Manning, Troy Aikman, John Elway or Terry Bradshaw -- but San Francisco never made it easy on him either.

There was the constant shuffling of offensive coordinators throughout Smith's career, the lack of a game-changing wide receiver to pair him with and even, perhaps most impacting of all, the thinking that he just wasn't ever going to be the guy in San Francisco.

Heck, following a 13-3 season and being perhaps just a fumbled punt return away from a trip to the Super Bowl in 2011, Harbaugh made a play to bring free agent Peyton Manning into the fold before losing out in that sweepstakes to the Denver Broncos. That's when San Francisco was able to re-sign Smith to a new three-year deal.

Maybe that was Smith's first real mistake -- he certainly hasn't been making them on the field over his last two dozen games -- putting his trust back into a franchise and head coach that were ready to kick him to the curb.

And that happened yet again despite Smith being 19-5-1 in his last 25 regular season starts since 2011; despite leading the NFL with a 70-percent completion rating; despite ranking third with a 104.1 QB rating; despite six fourth- quarterback comebacks last season and five touchdown passes to zero interceptions in two playoff games.

Harbaugh got his excuse to move on when Smith suffered a concussion against the St. Louis Rams on Nov. 11. Kaepernick came on in relief and helped San Francisco battle back for a tie.

Things got murky when Kaepernick started in place of a still-concussed Smith on Monday night against the Chicago Bears and engineered a 32-7 rout. Harbaugh declared that he would go with the hot-hand and that turned out to be Kaepernick in a 31-21 victory over the New Orleans Saints last weekend, with the former second-round pick getting the call despite Smith having been cleared for contact.

No one can deny that Kaepernick has done better than expected over his first two career starts: 66.7 completion percentage, three passing touchdowns, one rushing score and one interception.

But all he has really done is mirror to some degree what Smith has been doing since last season.

"Well, the rationale is you've got two quarterbacks that we feel great about as the starting quarterback," Harbaugh said when announcing Kaepernick as the starter on Wednesday. "Both have earned it. Both deserve it. Alex over a long period of time. Colin by virtue of the last three games. What tips the scale, is Colin, we believe, has the hot hand and we'll go with Colin. And we'll go with Alex. They're both our guys."

And that's not fair to Smith, nor is Harbaugh's refusal to commit to one quarterback for the rest of the season. There were other options for Smith this past offseason, less glorious but there nonetheless, and he decided to ignore San Francisco's public courting of Manning after the belle of the ball said no to a dance.

Now Smith is left standing at the altar while Harbaugh hops on the back of a motorcycle with the hottest new thing.

"You kind of state your case with your play. I felt like I had done that. So in that sense, it is tough," said Smith, adding that he doesn't know if he will get another opportunity under center.

And if Kaepernick does crash and burn down the stretch, and Harbaugh comes running back to Smith with big dangling diamond earrings, Smith should do what most parents tell their kids to do on prom night and just say no. He certainly doesn't owe Harbaugh anything.

The 28-year-old's resume as of late is good enough to get him a starting job next year without playing another down this season. Wouldn't the Minnesota Vikings or Philadelphia Eagles, just two of a few clubs that could add Smith to an offense with plenty of weapons already, love his efficiency under center?

One school of thinking is that Kaepernick will take chances with the ball that Smith won't, and that his legs give him another tool that Smith doesn't have.

But don't forget, Brad Johnson and Trent Dilfer have won Super Bowls this century and it's not like Smith sits on a barstool when he drops back into the pocket.

"Alex can run, too," said Rams head coach Jeff Fisher. "He extends plays as well, but not to the extent that Colin does. But, it's a challenge."

Football is a business, number one, and Harbaugh is doing what he thinks will get his team over the hump, but you also "dance with the one that brung ya."

Smith was that guy, but not anymore. And soon Harbaugh, with integrity that might be worth as much as Hostess stock at this point, won't have him to kick around anymore.