He wasn't thrust into a starting spot. Rivera gave it to him from the start, because he's an incompetent idiot. He knew he hated Jeff Otah and wanted him gone, and yet the team did not pursue another RT to compete for the job. That's is an utter failure by both Hurney and Rivera. I don't think Bell is ever going to "do well" at RT no matter who is playing next to him, because he isn't athletic enough to attempt to deal with anything above an average NFL DE.
Bell was given the starting job because there wasn't anyone else. That's not his fault, just like it's not Silatolu's fault that he was expected to jump from Division II college to starting LG in the NFL. These young OL can't help the fact that our team let our OL get into the condition it's in.
And yeah, Rivera probably did hate Otah, just like half the fan base and other coaches. Sure, he was a huge help when he was playing, but let's face it. He was fat and couldn't pass a physical and probably would've been on IR before week 2 anyway. I'd love to see the new GM build up our OL, since it appears that we're getting a pretty decent rotation on the DL. If we can build our team's trenches we'd be a lot better off.