Geno Smith throws a pass as he warms up for...

Geno Smith throws a pass as he warms up for a game against the New England Patriots. (Sept. 12, 2013) Credit: AP

As with most rookie quarterbacks, the growing pains are to be expected, and Geno Smith is no exception. Now it's a matter of how long the Jets can live with the mistakes and whether they'll simply sacrifice the season to see what they have in him.

Or is this not as open-and-shut a case as it might appear?

Even with Saturday's news that Mark Sanchez has been placed on injured reserve, with a designation to return after eight games, general manager John Idzik declined to say that Smith will be the starter for the rest of the season. Idzik said his rookie quarterback will start against Buffalo next Sunday, and that's as far ahead as he was willing to look.

That may just be Idzik's way of simply avoiding the subject of Smith's longer-term future, but it also might signal the possibility that the Jets will not simply keep Smith in the lineup just because they've invested a second-round pick in him.

It's early, yes, and the hope for the Jets is that Smith can grow into the job as the season progresses. But being a first-year starting quarterback in the NFL is not an exact science, and there's no guarantee that Smith will adjust to the pro game without committing more of the mistakes that held him back the first two games.

And that means coach Rex Ryan, who is fighting for his own future and needs to win games, doesn't have the luxury of simply watching a rookie quarterback take his lumps with no consequences. So if Smith continues to be a turnover machine in the coming weeks, there is no guarantee that he'll keep the No. 1 job. Even with Sanchez on the shelf for the next two months.

Ryan has the makings of a very good defense, and the running game appears to be reliable. That means he needs a game manager at quarterback, not someone who turns over the football the way Smith did Thursday night in New England, when he threw three fourth-quarter interceptions. That gives him five turnovers in his first two games, plus nine sacks.

Ryan doesn't have many good alternatives behind Smith. Matt Simms played well in the preseason but has no NFL experience, and Brady Quinn has never lived up to his first-round reputation.

Sanchez could return with six games to play, and the team has $8.25 million of guaranteed salary tied up in him. So it actually might benefit the Jets to have him play in the event Smith hasn't progressed enough, even if it seems as if they're ready to part ways with him after the season.

There have been some encouraging signs from Smith in the early going. He overcame a shaky start against the Bucs -- he lost a fumble at the Jets' 5-yard line to set up a Bucs touchdown -- and wound up on the right end of an 18-17 comeback win that required a huge assist from Bucs linebacker Lavonte David, who inexplicably shoved Smith after he ran out of bounds and incurred a penalty that set up the game-winning field goal.

If Smith does sputter, especially as the Jets get into the meat of their schedule after facing Buffalo and Tennessee, Ryan might have to at least consider a change, if for no other reason than to give Smith a chance to gather himself. Ryan had first-round pick Dee Milliner watch from the sideline after he was benched in the second half against New England.

The Jets certainly hope they don't have to go in that direction and that Smith will make a steady upward progression as the season unfolds.

The best-case scenario for the Jets is that Smith stays in the lineup for a prolonged period, but there have been too many examples over the years of young quarterbacks who need more time to become acclimated and just aren't ready in Year 1 to handle the starting job full-time. Especially when the coach is fighting for his survival and has a defense and a running game that are set up for a game manager as a quarterback.

Smith now has his chance during the next two months without Sanchez looking over his shoulder. The Jets can only hope he makes the most of it.

ONE-DAY SALE26¢ for 5 6 months