Last year was extended preseason.
Sort of.
This isn't an original thought, as if you listen to Jake Burns he's kind of elaborated on it, but the Browns tried to install 2 offenses last year. When the Browns saw the results of how uncomfortable the whole team was in the Houston game, Stefanski pulled the plug and went back to the original, under center offense. For as good as Watson is as a QB, he's not really an under center the majority of the time guy. He loves being back in shotgun, looking at the coverage and then making his decisions. He doesn't love compact football, he likes to spread the defense and make a play.
The results became a heavily predictable offense (run scheme was basically all outside zone and pin pull while the passing offense was play action and simple routes) and a defense that couldn't compete with offenses because of their complicated scheme rules. A lot of people were focusing on Pocic's injury as to why the Browns failed to run late in the season, but the reality was that teams knew their looks and knew their run schemes to a T. Especially when they were running out of shotgun. It was simply too basic and did not threaten a defense at all.
I expect the offense to look so radically different than anything we saw last year. The Browns led the NFL in empty this preseason, and I expect that to continue, because Watson was easily the best empty formation QB in the NFL by a wide, wide margin from his draft year thru 2020. You're also going to see a lot of inside zone runs from shotgun this year, because you can run zone read and RPO's off inside zone runs. You cannot do it, or at least not very easily, on outside zone.
Ultimately, I think the worst we'd see of Watson this year would be a mid tier QB, but there is no reason for him to be that bad. This is the offense and style that he is most comfortable in. He should rip the NFL to pieces again, maybe even at a better level than before, because inside zone/zone read/RPO's should be deadly between himself and Nick Chubb. Should be unstoppable, if I'm being honest.