Jameis Winston and Marcus Mariota are going to be measured against each other for their entire careers, and we can already see the analysts starting on that storyline. In an exhaustive look at both Marcus Mariota and Jameis Winston, Cian Fahey of Bleacher Report concludes that Mariota's more likely to succeed early on, primarily because of the Tampa Bay Buccaneers' shaky offensive line and the more spread-friendly offense the Titans are implementing for their college passer.
We've talked about the line over and over again, but the team's scheme hasn't been mentioned often. Dirk Koetter ran a very vertically-oriented scheme in Atlanta, with the four verticals concept being the core of everything he did there. Matt Ryan's stationary pocket-passing style should carry over to Tampa, as Winston is a fairly similar passer, stylistically. There have been no hints that the Bucs are making any kind of special adjustments to the offense for Winston. Instead, Koetter has emphasized how much Winston learned in college, and how quickly he's absorbing his scheme now.
Contrast that with the Tennessee Titans, who are adjusting to Marcus Mariota's strengths. Or at least that's what they're saying, likely inspired by the early success of Robert Griffin III, Cam Newton and Colin Kaepernick in offenses that did much the same thing: offer a similar environment to these quarterbacks' college schemes to ease the transition -- something made easier by the increasing spread influences in the NFL game itself.
Of course, the Bucs don't need to do that. Winston's a traditional pocket passer. His college scheme will be similar to what he'll play in now, without the need for any special packages. But that doesn't mean we'll necessarily see early success: rookie quarterbacks from more traditional offenses haven't hit the ground running in recent years. Even the constantly praised Andrew Luck was just okay in his rookie season.
Ultimately, though, the speed with which each quarterback adjusts to the NFL is going to be a lot less important than their long-term development. These players may carry their teams for 20 years or so, when all's said and done. Whether Mariota or Winston looks better after one year is not going to be the measure of their career success.