You know that excitement Case Keenum managed to infuse the Houston Texans with? That temporary sense of hope?

It all may turn out to be one of the biggest miracles of this NFL season. For with Matt Schaub back behind center, the Texans show how lifeless their offense truly is. Schaub throws two fourth quarter interceptions, gets sacked on back-to-back plays to kill a critical third quarter possession. Peyton Manning powers through a near heroic effort from Wade Phillips' undermanned defense for the first three quarters — and hits the Texans with three fourth quarter touchdown passes.

Denver Broncos 37, Houston Texans 13.

This is life with Matt Schaub at quarterback. Dead team walking. Just waiting for the next big mistake.

"It is a huge blow," Texans rookie safety D.J. Swearinger says of Schaub's first interception — a forced pass to DeAndre. Hopkins with Schaub on the run — and the defense allowing a quick Broncos score after. "Any time you turn it over and give up a score, it's like a dagger into your own team, a dagger into your spirit."

Yes, these Texans are fragile — for good reason. Experience hasn't been kind to them.

It all makes what Case Keenum accomplished . . . yes, accomplished . . . as a first-year starting quarterback all the more impressive. No, he didn't win a game. But Joe Montana in his prime might have some difficulties winning a game with these Arian Foster-less, dispirited Texans.

Tearing ligaments in his thumb and seeing Phillips turn back to Schaub rather than T.J. Yates for some still inexplicable reason may turn out to help Keenum in the long run. For Schaub's performance Sunday proves Keenum played much better in his time starting than a Houston media core that is eager to dismiss him is willing to admit.

A 24-point loss to a Denver Broncos team experiencing some late-season issues of its own shows how little there is to work with for any quarterback.

Yet, Keenum keeps the Texans in close game after close game for weeks. He stares down the specter of Bill Belichick and puts 30 points up against the New England Patriots, loses by one to Tom Brady in a shootout.

Schaub cannot come close to doing that against Manning in a similar Reliant Stadium situation. Not even on a day when the Texans defense plays great for three quarters.

Does this mean that Case Keenum is guaranteed to be a successful NFL starting quarterback? No. But it sure shows he deserves a chance.

It's now clear this mini, twice-interrupted run this season isn't close to a fair barometer. Not with the state this Texans offense is in.

Keenum's played well enough to be given the opportunity to compete for the starting quarterback job in training camp. Given the state of the Texans quarterback position, it'd be a huge mistake for the team to do anything but that. Whether general manager Rick Smith reaches and takes one of the hardly surefire quarterback talents with the No. 1 overall pick or waits until early in the second or third round to draft a QB, Keenum must be given equal opportunity with the new guy.

Otherwise, the Texans risk throwing away a potential valuable asset without ever knowing how good Case Keenum can be for sure.

Look at Nick Foles' jump in his second season starting in Philadelphia. Foles went 1-5 as a starter his first year playing for a bad Eagles team. Is that really much different from Keenum's twice-yanked 0-8 mark with a historically inept Texans team?

Now, Foles cannot stop throwing touchdown passes — and winning under a new head coach. Is Keenum sure to make a similar improvement under the Texans new head coach? No, but he's got a shot to if he's given the chance. Keenum's talent and work ethic ensures that.

He spends this Sunday on the sidelines in a baseball cap and a windbreaker, his right thumb in a splint. Keenum's animated and into the game, discussing plays with Schaub between series, trying to help the guy who's helped him since he first signed with the Texans as an undrafted free agent.

Schaub's Reliant Stadium goodbye isn't storybook. It's just sad and fitting.

"I think Matt’s a great player," veteran receiver Andre Johnson says. "If he’s not here, he’ll get another opportunity. Matt can start in this league. He’s done it for eight seasons. Sometimes a fresh start can be something beneficial."

When Schaub trudges off the field, no one is seeking him out. Instead, lifeline Texans Andre Johnson and J.J. Watt make sure to pay their respects to Peyton Manning for his record-breaking 51 touchdown passes. Schaub joins that Manning receiving line too.

"It has definitely crossed my mind," Schaub says of the likelihood of this being his last game in Houston. "I didn't want to think too far ahead, but you know I've played this game long enough. I know how things work.

"So you know it definitely crossed my mind."

The Anti Keenum?

Schaub leads one impressive drive all day. A third quarter march punctuated by a touchdown strike to Keshawn Martin in the corner of the end zone.

That's the kind of thing — one good drive — that got Keenum benched when Gary Kubiak still coached the team.

Schaub completes less than 50 percent of his passes (18 of 37), a lower percentage than Keenum recorded in any of his eight starts. Maybe there are circumstances that make having a high completion percentage with this battered, beaten down Texans offense impossible for any quarterback.

It turns out playing quarterback for a dead team with absolutely no running game and one dependable wide receiver is harder than many think.

And Schaub does a much worse job of it than Case Keenum.

Schaub throws a three-yard pass on third-and-10. He completely overthrows Johnson on a touchdown chance, flinging it out of bounds to leave the Greatest Texan Ever futilely extending his fingers.

All before the end of the first quarter.

When Schaub is sacked by Broncos defensive tackle Sylvester Williams, he drops to the ground before Williams can even hit him. Hey, he needs to be healthy for his new team next year.

With six minutes left in the first half, the Texans are one for six on third down and Schaub's hearing his first real boos of the day. The rightful trigger? Schaub tentatively stepping a few steps forward in the pocket and flinging a no chance short pass sort of toward Johnson on a third-and-11 deep in Broncos territory.

It's an eye opening exhibit. It shows just how bad these 2-13 Texans really are.

"I'm not sure we put together one full game all year," defensive end J.J. Watt says.

Truly evaluating a young quarterback amidst all this misery and ineptitude is impossible. It's amazing Case Keenum managed even stretches of brilliance. Every Matt Schaub pass makes him look more and more promising.