The only fair comparison is how Cleveland was doing in the same timeslot at the same time last year. According to Wikipedia, Cleveland's ratings on Jan 10 2010 were 8.54 million, which I'm guessing was following football playoffs. The next few weeks it was dramatically down - Jan 31 4.53, Feb 14 4.85, and Feb 21 5.60. Now when fall 2010 came around, it was regularly seeing 6.5-7.0 again, but once again when January rolls around it's back to the high 4's - low 5's (except for Jan 9 when it was following football playoffs again, it got 7.38), but that was in the 9:30 slot so it's not exactly apples and oranges.
Now this is a very small sample size, but so far Bob's appears to be following about the same exact trend. On Jan 9 2011 it saw big ratings following football playoffs - 9.38. Then it dropped off in the following weeks - Jan 16 5.07, Jan 23 4.81, Feb 13 4.19, Feb 20 4.87. That's about the same as Cleveland at the same time period, in the same timeslot last year. So, I'm not sure how one would come to the conclusion that it had "far better ratings" at 8:30, unless you're talking about it's 2 fall seasons which isn't a fair comparison (and it wasn't even that much better in fall 2010).