Let's not get crazy, it was one game in the beginning of the preseason. With a very limited sample size (39 snaps for Jameis Winston and 20 snaps for Marcus Mariota) this is just a brief look at how each team started.
This is a look at the information we know:
While some will argue that Mike Evans not playing was a big impact on Jameis Winston's effectiveness. However, with Delanie Walker on the sidelines you could easily say that both lost one of their top two pass catchers.
On the offensive line neither had a huge advantage, but the difference was Taylor Lewan. Lewan locked down his side in pass protection and was constantly on the outside securing blocks, once on a big screen and once on a touchdown run. However Winston was constantly under fire and you could tell it was affecting his mechanics. He isn't the quick twitch athlete that Mariota is in that he can roll out and make a play.
With that, the unfortunate news for Bucs fans is that their starting right tackle is now out for the season with a knee injury, so this will probably only get worse for the rookie.
The stat lines
Keep in mind that Winston played twice as many snaps as Mariota here:
Mariota: 7-8 (88% completion), 94 yards, 11.8 YPA, one INT, one sack
Winston: 9-19 (47%), 131 yards, 6.9 YPA, one INT, two sacks
I will admit I am biased, but I would much rather have the Mariota stat ine here. His one incompletion was an interception I believe, which means outside of a miscommunication that was largely Bishop Sankey's fault he was nearly flawless.
Winston had a rough night and really didn't get into a rhythm of things until the second string defense came out and started playing softer coverages.
Finally, here are their PFF scores from their performances:
So it isn't a wide margin that separated the two, but there is a clear winner in my opinion. Honestly, this isn't something that you can figure out by 20-40 snaps, but if I were a Titans fan I would be happy that Winston struggled so that you don't have to hear all week about how Winston was the right choice.