The Bucs run defense has been a weak spot for two seasons now, and Barrett Ruud has been appointed the main culprit by people. This assault on Barrett Ruud was spearheaded by radio host (and former Buc) Ian Beckles, who can't stand Barrett Ruud's lack of physicality. And he has a point: Ruud is not the most physical linebacker, he has trouble shedding blocks and he's not a big hitter - he's a drag-down tackler. Certainly, he can be upgraded and he's not the best player against the run. I dispute none of that. But at the same time his lack of physicality is not the reason the Bucs have been unable to stop the run these past two seasons.
Instead, look at players like Geno Hayes and Sabby Piscitelli. In the Bucs' one-gap defense, the run can be stopped without big hitters at linebacker, even with players who get dragged for a yard. But it's impossible to stop the run with players who are out of position and miss assignments. When a defensive lineman gets pushed out of his gap (as happened to Roy Miller with regularity last season), or gets trapped, the Bucs can't stop the run. While the Bucs have added talent to address that, the defensive line was still a weak point in the run game last season.
Ruud also has plenty of good qualities. He is on-point in his assignments, he knows this defense like the back of his hand and always gets the defense in position. That can't be overestimated, and it will be nearly impossible to get anyone else to that level this year, or even the year after that. That doesn't mean it would be a disaster to leave him, he is replaceable and he's not worth a major contract. But he's useful to the Bucs' defense. There's a reason he has started for four years instead of other, more physical linebackers the Bucs have brought in.
Don't throw yourself off a bridge if Ruud is re-signed, even if you hate the player. Ruud is good in coverage, and while he is not the most physical linebacker, he is on his assignments and will not be a liability against the run. Don't blame him for the run defense, and don't expect the run defense to be magically solved if he's replaced by Tyrone McKenzie or Mason Foster. It will take a lot more than that.