Bruno wouldn't lose to Maskaev (twice), or Ruiz for that matter. I'd say this supports the very opposite of what you are claiming.
Well he also has a very good jab that troubled pretty much everyone he fought outside of Tyson. I seem to recall Peter dropping Toney with a jab.
TBH I never really rated Frank's jab. It was long and muscly but never seemed to have a lot of snap and he was so slow and lumbering I can see James slipping it fairly easily. On the other hand I am starting to agree with other posters that I am overrating Toney at HW and underestimating the shear size of Big Frank. I need to rewatch the Peter fights again as well as I am sure you are right in this.
He might. He’d lose at least one of those fights. And he’d definitely get laid out by Corrie Sanders and stopped by Lewis (happened).
Masakev had a bit of shaky chin he was stopped over half a dozen times in his career he would be vulnerable to Bruno's power, and Ruiz is well mediocre I don't see him beating Bruno. Sanders on the other hand would have a good chance of beating Bruno.