I literally don't think a single MW-SMW in history exists that could steal a round off SMW Bob. I think this is the theoretical Modern p4p GOAT. Unless Marciano comes up from Featherweight he might steal a few rounds because of his work rate before being murder stomped.
I don't know why he would? He had the power to hurt anyone at 175 so why move down. If anything I could see him moving up to cruiserweight with his frame.
Ward and Roy would beat him. I'd also bet on Calzaghe. If someone like Zurdo or Benavieez Jr. entered the ring at like 185 that also might be too much for him, based on his career results.
He would murder all of them (I don't know about Andre)- I don't see RJJ taking a single big shot from a prime Foster- I don't know a lot about Ward though I will be honest so you might have me there? But the rest I am comfortable picking Bobby to take there souls.
Bob has a lot of hype but has a really thin resume considering...best win is probably a blown up ancient Dick Tiger. He lost to everyone decent he fought who was even a little bit over 175, so no he wouldn't do well against the huge guys drying out to 168 today. He's really poorly suited for today's era.
The lowest Foster weighed in his career was 170 and he was generally on or around the light heavy limit (apart from when he was stepping up to heavyweight and he didn't add that much weight even then). He didn't ever look like a guy who had many pounds to shed - he was a perfect light heavyweight, made for the division. He probably could just about shed the half stone with day before weigh ins but we don't know how that would effect his performance. It could weaken him.
I'm torn between my weakness for revisionist, iconoclastic history and a thrill of sadistic interest in seeing Foster against light middleweight opponents...