Gregg Rosenthal

It’s hard to imagine a regular-season Colts game without Peyton Manning.

The last time it happened was Dec. 21, 1997. Jim Harbaugh, now the 49ers head coach, started for Indianapolis that day. Current Colts left tackle Anthony Castonzo was gearing up for his 10th Christmas.

The NFL without Manning is equally disarming, especially for a few months. His play has been the constant in the league over the past 13 seasons. In an era of worst-to-first, Manning’s Colts have been to the playoffs nine straight seasons and 11 out of 12 years.

Manning’s latest setback after neck surgery told us this season is going to be different, no matter how it ends. Once the surest bet in the NFL, Manning’s Colts face the great unknown.

Nobody knows
On June 1, Colts vice chairman Bill Polian said he had “little or no worry” about Manning’s second neck surgery in as many years. The Colts thought Manning would be ready for training camp. On July 22, Colts owner Jim Irsay said he wasn’t worried and expected Manning to be ready to play. And then Irsay gave Manning the best contract in league history.

And on Thursday, Peyton Manning underwent neck surgery and could miss up to 2-3 months. That ends his streak of 227 consecutive starts, including the playoffs.

No one knows when Manning will truly be healthy again. This isn’t a knee sprain that Manning can gut out. It’s nerve regeneration.

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Manning was lightly practicing last week, but he was unable to throw like he usually does. After experiencing back pain and meeting with specialists, Manning was completely shut down. Keeping the quarterback out of practice is more alarming than the Colts calling Manning “doubtful” for the opener. This could take a while.

Life without Manning
Manning has won four MVP awards. They didn’t all arrive in best seasons, but they were all well-earned because no player is more important to his franchise.

The Patriots won 11 games without Tom Brady in 2009. Indianapolis would be lucky to win six without Manning. New 39-year-old backup quarterback Kerry Collins can’t learn the “Colts offense” because you can’t separate the playbook from Manning.

Manning earns his money as the team’s quarterback and offensive coordinator. He calls the plays; he sets protections; he perfects his timing with random receivers from Blair White and Jacob Tamme to Pro Bowlers such as Reggie Wayne and Dallas Clark. Manning makes it all go.

The Colts picked up Collins too late, midway through training camp. That move alone tells us the team was caught flat-footed by Manning’s injury. It tells us that the Colts have no idea when Manning will be back. They just want the best chance possible to stay afloat in the meantime.

So is it possible?
The Colts’ offensive line was a sieve last season. It has been almost completely remodeled for 2011. That should be a good thing long term, but raises questions right now.

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Castonzo, a rookie first-round pick, might not have the quickness to play left tackle on turf. Right tackle will be manned by second-year undrafted player Jeff Linkenbach. Collins might be the only quarterback in the league less mobile than Manning. Unlike Manning, he won’t be able to save himself by setting the right protections so easily.

It’s not like the Colts can rely on their ground game. They have been among the least-effective rushing teams in football three years running. Without Manning, Indy goes from a top-5 offense to one that could be among the worst in the league.

The receiver group remains an asset. But so much about what makes Wayne, Clark and Austin Collie great is that they know how Manning thinks. With Collins in the game, that mental synchronicity evaporates.