Let's start with the obvious: how you look in the preseason is not necessarily how you'll look when it counts.

When you're coached by Jim Harbaugh, that's especially true. Some coaches want to use these games to establish a rhythm, try out some new tricks. But Harbaugh seems to have two simple goals. Stay healthy, and show nothing.

Take the third preseason game, the supposedly all-important dress-rehearsal. Last year, against the Texans, the Niners looked completely inept, and yet it didn't matter at all. So no; when the Niners look flat in these preseason games, there's no reason to panic.

Good thing, too.

In Denver, the starting O had precisely one impressive play: a beautiful touchdown pass from Alex Smith to, of course, Vernon Davis, who was five yards away from the closest defender. (To be fair, that was one more impressive play than was made by the starting D.) But the enduring image was a head-shaking sequence of follies worthy of Jimmy Raye: timeout, delay of game, false start.

And with that, mercifully, the preseason for the starting O was essentially done.

But Colin Kaepernick was just getting started.

As recently as the week before, he looked like he hadn't improved at all. Still a physical freak, of course—the strongest arm imaginable, and seemingly faster than any receiver—he was struggling with two very serious issues. Like most graduates of one-read college schemes, he wasn't exactly zipping through progressions. But even when he found the open man, his lengthy wind-up—consuming nearly every inch of his infinite wingspan—seemed to make him flatly unable to deliver on time. Finding the window was tough enough; by the time he was able to fire the ball, the window was closed.

These same red flags were on his draft-day scouting report, and despite a year of Harbaugh's coaching, they were still there. Harbaugh deemed him a lock for the #2 job, but this seemed like more of Harbaugh's patented coachspeak. Kaepernick was Harbaugh's Chosen One; naturally Harbaugh would pump him up. But on his actual merits, Kaepernick was barely ahead of #3, or was even #3 himself.

In Denver, though, something changed.

Oh, it was subtle; Kaepernick threw the ball only four times. But they might've been the four best throws of his career to that point. A 30-yard rope on a roll to the left. A perfect strike on a three-step drop. A gentle touch on a roll to the right. And a bullet perfectly placed into coverage.

That was all, but something was different. The decisions were quicker, more assertive; the delivery seemed tighter, more efficient. And surely you noticed: the entire offense crackled with life.

And we hadn't seen anything yet.

On Thursday night, he did it all. He threw from the pocket. He threw on the run. He threw for two spectacular scores. Every throw, except for four, went more than 10 yards. And every throw, except for two, was on time, and on the money.

Now that was an explosive offense.

Okay, let's calm down a bit. Drool-worthy showings by backup QBs are standard fare in preseason games. (See Davis, Nate.) Coaches tend to open their playbooks for the backups—even Harbaugh seemed to here—and the opposition is hardly elite. It pays to remember, the preseason is still just that: nothing's as bad, or as good, as it looks.

On the other hand, though, this wasn't some no-name we picked up on waivers. This was our designated quarterback of the future. And out of the blue, it looked like the future was already here.

Now understand: I am not suggesting that Kaepernick should start, or start right away. No doubt, it's tempting; with no fewer than 10 teams about to start first- or second-year players, it's now become clear that the learning curve for young QBs—and the conventional wisdom that they should be treated like they're made of glass—is a lot less imposing than it used to be. Add to that their athletic chops—exponentially more jaw-dropping than those of their veteran peers—and the Niners might steal an extra glance or two at Kaepernick, perhaps the most athletic of all.

The thing is, though, none of those 10 teams are Super Bowl favorites. Put another way, they've got nothing to lose. But the Niners are ready. Sure, trying to win largely with defense and ball-control might seem hopelessly old-school, but last year they nearly won the whole thing. They'd be crazy to upset the apple cart, right?

Yet the Niners know they can't expect to ride that same cart all the way once again. They can still stay balanced on offense, of course—their D and their special teams would seem to demand it—but they know the 29th-ranked passing O will not be enough, not this year. Today's league just won't allow it. If the Niners get halfway through this season, and if they're still throwing for 183 yards per game, they won't be on the path to the title.

In light of last year's shocking success, Smith deserves this chance he's got, to prove that he can raise his game. I'd hoped that he'd prove it this preseason, and now I hope that his failure to do so is attributable only to Harbaugh's refusal to tip his hand. But this preseason proved something just as important.

If Smith doesn't step up....?

Kaepernick will be waiting.