HOUSTON - Be careful what you wish for.

Nick Foles' left shoulder got pile-driven into the turf at NRG Stadium on the last play of the first quarter, and, suddenly, the Eagles' quarterback discussion became real.

Yes, backup Mark Sanchez showed remarkable command of an offense that he had never before run in a game. He connected on a 52-yard bomb to Jeremy Maclin, his first play as an Eagle; a testament to Chip Kelly's faith in his veteran backup.

"How about that, huh?" Sanchez said afterward, his blinding smile contrasting nicely with his eye black. "I was expecting maybe a handoff, or maybe a screen, to kind of ease my way in. If [Kelly] was a basketball coach, he'd bring you off the bench and have you shooting three-pointers."

He might not be a better passer, but Sanchez is a much better quote than the starter, anyway.

Sanchez later found big rookie Jordan Matthews in the end zone over little Texans corner Andre Hal, and found Maclin in the end zone for a clinching score in the fourth quarter.

Sanchez appeared to have no problem translating and executing the offense. He routinely and smoothly checked down to secondary receivers.

So what?

Sanchez also threw three lousy passes in the third quarter; one, unpressured, into triple coverage; another, pressured, far behind his receiver; and the third, unpressured, into double coverage, which Jumal Rolle intercepted.

Sanchez finished 15-for-22 for 202 yards with two touchdowns, two interceptions and two other throws that could have been disastrous. It was as if he channeled his Rex Ryan Experience.

Most significantly, as always, the Eagles won, 31-21.

Was there ever any doubt?

"I've never in my life been more confident on any team with a backup quarterback than I am with Mark Sanchez on our team," linebacker Connor Barwin said. "He fit into the culture of our locker room from Day 1."

Fitting into the culture does not necessarily mean fitting into the scheme, though Sanchez clearly does. If anything, the Eagles' Machine Gun offense ran faster, if not better, with Sanchez in place of Foles.

Sanchez certainly didn't look like a player who hadn't thrown an NFL pass in 22 months.

"This league will expose you," he said. "It's been a while . . . I felt like I was ready. I was prepared. You want to get the first throw out of the way, and thanks to Chip we throw it right down the field. That'll get your nerves gone."

He'd been more nervous in the past on the same site. Sanchez debuted as a Jets rookie in Houston.

"That brought back some good memories," Sanchez said. These were the memories: 18-for-31 for 272 yards, a touchdown and an interception in a 24-7 win Sept. 13, 2009.

"I thought he had real good command of what he was doing," Kelly said. "I don't think we missed a beat."

Oh, Sanchez missed plenty of beats.

But, on this team, that's OK. It is a tight-knit group that simply lacks angst.

Other Eagles editions in the Jeffrey Lurie Era have had actual quarterback controversies: from Randall Cunningham's end to Rodney Peete/Ty Detmer to the Bobby Hoying Disaster to Donovan McNabb vs. the World to Kevin Kolb/Michael Vick. Each of those caused locker-room strife.

Whether Foles returns quickly or whether Sanchez runs this season's table, this will cause no strife. In the locker room and in the front office it is decided: Foles is the quarterback; the future, for better or worse. Sanchez is the backup; capable, professional, but demonstrably flawed.

Yesterday, against a ravenous defensive front, neither Foles nor Sanchez had much of a chance to settle in early.

"Holy smoke, they were coming over the walls," said Kelly, whose passers were sacked twice apiece and hit about a half-dozen times each.

They had no chance behind a line with a one-armed guard, Todd Herremans; who, mercifully, was benched with an ankle injury midway through the third. Herremans began the game with a biceps injury. The Eagles drove 70 yards on four runs for a touchdown on their first drive without him. Despite Herremans' best efforts, that left arm mainly served as a turnstile for Texans lineman J.J. Watt.

They had no chance behind a line centered by Jason Kelce, back for the first time in four games after undergoing sports hernia surgery. Apparently, the injury causes high snaps.

Certainly, those issues did not help Sanchez; but then, he has always had apologists.

They defend his mediocre run as a Jet by pointing to a lack of weaponry, lack of protection and too much pressure; being the fifth overall pick and playing in New York . . . as if Sanchez had no responsibility for his career passer rating of 71.7.

As always, he wasn't totally at fault. Right?

Sanchez's first interception bounced off the hands of Houston homeboy Josh Huff. On his second interception, Kelly said, Riley Cooper "got spun around."

To be fair, Foles sometimes looks like he's the one who hasn't played in 22 months.

But only sometimes.

Foles threw a lovely, 59-yard bomb to Maclin in the first quarter, his 13th touchdown. Those scores have seemed more an exception than a rule in 2014.

Foles' passer rating entering the game was 80.7, worst among quarterbacks with at least 250 attempts. Only two quarterbacks threw more than his nine interceptions - he added another late in the first period - and he lost three fumbles as well. The Birds were last in red-zone touchdown percentage.

All of which led to a moderate cry for his replacement.

The team was 5-2 coming into Houston, and Foles made the Pro Bowl after just 10 starts last season, when he threw 27 touchdowns and two interceptions and stole the starting job from fading star Michael Vick.

Certainly, Foles has a lot to learn. He cannot make a living throwing off his back foot, flustered by phantom pressure. He cannot expect to make strong-armed throws with an arm that just isn't that strong.

Not that Sanchez has a howitzer.

No matter which quarterback runs the team, the Eagles will be competitive only with a solid running game and a sound defense. In Houston, against a defense that lost both starting corners and had an eroded front seven, the Eagles had both. The Texans scored all their points off Eagles turnovers.

The difference between the quarterbacks is simple.

In his third season, at 6-6, 243 pounds, with a fine football mind, there is, for Foles, a promising ceiling.

There is, in Sanchez, mainly promise unfulfilled.