Cam Newton started immediately last year, and excelled immediately. He famously became the first quarterback to pass for over 400 yards in each of his first two games, kicking off a record-setting year.

That conveniently and quickly made us forget about how horrid he was during the preseason, when he completed only 42.1 percent of his 57 passes, and averaged only 5.3 yards per attempt. Even a rookie who shattered records had a learning curve, albeit a much shorter one due to his superior skill as a No. 1 pick, and is ability to compensate with his legs.

Ryan Tannehill’s curve may be far more difficult to navigate, which is why despite his status as the caretaker of the Dolphins’ future, the same fans who plastered the city with Manning to Miami Billboards should expect to see either Matt Moore or possibly Chad Henne under center for a chunk of the 2012 season.

That was the consensus when Brian Biggane of the Palm Beach Post talked to several draft experts who’ve watched more game tape over the last few months than the normal human mind and eye can tolerate, and a hall of famer who may know something about playing the position.

The hall of famer was former Dolphin Bob Griese, and he pointed to another former Dolphin who took a nice warm seat during the first part of his career, noting that Dan Marino didn’t start until nearly halfway through his rookie season.

Mike Mayock doesn’t belong to football’s old guard, and is instead among the chronic tape watchers. But he agrees with Griese, saying that Tannehill will be roasted if he starts right away.

“When he throws anything outside it’s beautiful, and they’re easier reads. Some of the in-breaking routes he struggles with. I talked to him about it on his Pro Day, how (he) stares down receivers, pats the ball, doesn’t show confidence, and he said, ‘You’re right, that’s what I’m trying to work on, to trust my reads.’

“He’s not ready. I think he gets eaten alive this year by NFL defenses.”

Greg Cosell, the NFL Films analyst who watched quite literally all of Tannehill’s throws for the Aggies in 2011, was the lone voice of disagreement.

“He has elements in his game that transition very well,” Cosell said. “He’s a very comfortable pocket player (and), given his lack of experience, he has excellent pocket movement. I thought he threw to the outside very well, and you don’t see that often in college football.

“He also threw the ball on the run better than (Robert Griffin ) and (Andrew) Luck, which means you’ll see them employ a lot of play-action passing.”

When Tannehill gets slotted ahead of Luck and Griffin in any context, that’s lofty praise, and it’s easy to flip back through recent years and hand pick rookie QB success stories beyond Newton and Andy Dalton. What you’ll find, though, is doing the opposite is just as easy, and the young arms who succeeded have generally had far more support than what Tannehill will have in South Beach.

Two years ago Sam Bradford set a rookie record for completions, an incredibly overrated feat he accomplished through a perfect storm of factors that allowed him to be a blatant compiler. He ranked 31st in net yards per attempt, ahead of only Jimmy Clausen, which is several stratospheres below superstar status.

Bradford benefited from the support provided by a younger Steven Jackson. Tannehill will have Reggie Bush and Daniel Thomas in the backfield, two talented but highly injury prone runners. He also won’t have reliable targets following the departure of Brandon Marshall, which leads to Davone Bess’ ascent up a weak depth chart. Matt Ryan had Roddy White in 2008, and White had 1,382 receiving yards that year.

Wide receiver is the most glaring hole on Miami’s roster. If they start Tannehill in Week 1 when he’s far from ready and when he still doesn’t have a consistent deep threat, the Dolphins risk needlessly shattering his confidence during a year when they’re not realistically contending anyway, and turning him into Blaine Gabbert circa 2011.