Outside of their sexual assault allegations Watson and Roethlisberger aren't comparable.. 2 completely different QBs, 2 completely different builds, and 2 completely different eras (game was just more physical when Ben came up).
Big Ben in his younger years could move for a man his size, but that wasn't what made him dangerous.. He was just so damn hard to bring down. He was a anomoly, basically damn near undersized lineman playing QB. He would punish defensive players just as much as they punished him. Led to all the injury issues he had later on in his career, but also is what made him a great QB. He could stand tall in the pocket, take a hit/contact, break out of tackles, and still make throws downfield.
Watson can hurt you also, but totally different style. Difference is Watson doesn't have the style where you can sit back there like Ben did. I think his best season or atleast the best I thought his skill set blended and maxed his talent potential (here anyway) was his rookie year playing in the RPO. I was a huge Watson fan.. even said he was a top 5 QB, but even I saw him run into self inflicted sacks regularly. That's the part of his game he has to change if he wants to take the next step. Athleticism/youth only lasts so long and takes you so far at that position.. If Watson wants to play as long as Ben did (39 yo) He's going to have to make a transition just like Ben did. Roethlisberger even figured out he couldn't just hold on to the ball and try to make hero plays.
Sometimes I feel like Dabo Sweeney did Watson no favors by calling him the Michael Jordan of football.. there is no such thing (closest outlier is Tom Brady). Out of all the big 3 sports, basketball is the most individual driven team sport there is. Football is the complete opposite of the big 3. Where Deshaun always got into trouble is where he tried too hard to make a play instead of just avoiding a negative one. Yeah, when he had his "Houdini plays", much watch TV.. but more often than not it didn't go that way. That style of play wasn't sustainable. He's got maturing left to do on the field and a hell lot of it to do off the field.