MIAMI GARDENS, Fla. – Full disclosure before we start today’s lecture – it was composed a few hours before kickoff of the Titans’ seven-hour, 27-20 loss to the Miami Dolphins on Sunday at Hard Rock Stadium.

And this is because nothing that happened Sunday was going to change the parameters of discussion when it comes to Marcus Mariota this season. Not even a Sunday as outrageous as this one. Those parameters are as follows:

• This is obviously a crucial season for Mariota’s future and his future with the Titans, and it will be a full-season evaluation. He will have surges and lulls.

• The dip he and the Tennessee offense experienced last season prompted Titans brass to change coaches, and that move will be seen largely through the prism of his performance.

• The reality of the rarity of finding people who can play NFL quarterback well tells us it would take another dip from last season’s performance for the Titans to seriously consider moving on from Mariota. If he is this season the average of what he has been in the first three, I think a long-term extension is an easy choice.

• Everything that goes wrong in the passing game isn’t his fault. Everything that goes wrong in the passing game can’t be all everyone else’s fault. All quarterbacks are prone to drops, bad routes, bad protection, bad play calling and a weak running game, but there are always plays to be made and the good ones make enough of them.

• Backup Blaine Gabbert is not and won’t be a competitor for Mariota’s job. Ever.

That’s it. End of lecture. Leave your apples on the desk and your chiding emails in the inbox. Now we can talk about Mariota’s season-opening performance in that context, and do it again after the Titans open at home Sunday against the Houston Texans, and keep doing it until we have a strong idea of how this will go.

Mariota was not very good Sunday, and he was really bad after a shoulder/elbow injury robbed him of some feeling in his fingers. He floated two passes that turned into interceptions and sat the rest of the way. He finished 9 for 16 for 103 yards, no touchdowns and the two picks, for a tidy quarterback rating of 37.4.

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He said afterward he probably should have thought better of returning after the injury. The injury, by the way, came on a hit that should have seen William Hayes penalized for unnecessary roughness. The fact that it was a handoff on a run/pass option does not change the fact that even quarterbacks who have the ball would be protected with a flag there 99 times out of 100 in today’s game.

So there are excuses available for Mariota. His favorite target, Delanie Walker, likely will not be available to him for the rest of the season because of a gruesome leg injury late in Sunday’s game – a huge blow to Walker and this team. That can be a Mariota excuse, too.

To be clear, he isn’t looking for any. But he has to get back healthy fast and figure things out fast to give the Titans a chance to avoid an early hole they might not be able to exit. After the Texans, it’s Jacksonville on the road and Philadelphia at home.

Anything less than Mariota at his best might mean 0-4, and he was far from his best in the opener.

“Like everybody else, I thought there were times where it looked like he was confident and comfortable, doing some good things,” said Titans coach Mike Vrabel said, who consistently tries to avoid the singling out of Mariota even though it won’t stop the rest of us. “And then like a lot of other players and a lot of coaches, it just wasn’t good enough in the end.”

Mariota and this offense are still new to each other, and Matt LaFleur is his fourth play-caller in four years. Both handy excuses. But early in Sunday’s game when the Titans could have taken control of the game, Mariota’s lack of precision was the problem.

A bit behind Luke Stocker on a crafty play-action pass that should have scored. Late throwing to open Walker in the end zone. Not leading Corey Davis correctly on a fourth-down play that was stopped short.

“If I give him an accurate ball,” Mariota said of Davis, “I think he probably could have scored.”

He’s probably right. He’s always accountable. But this is a discussion about performance, and the Titans need it to change quickly.

Contact Joe Rexrode at jrexrode@tennessean.com and follow him on Twitter @joerexrode.