I'll stick my neck out and say that I think the first two Ravnica sets will underperform. I get the sense that Dominaria has been a success in part because they spent loads of time thinking "this might not be a success, so we'll need to think very hard about how to make it one," and that for Ravnica they went "we don't need to do that for this, as it will certainly be a success." I'm not confident they've thought that certainty through, although hopefully I'm wrong and they have.
Ravnica 1 did fantastic, but Ravnica 2 was not the total slamdunk they were expecting.
They caught a lot more flak than expected about it. That isn't making a statement of success or lack of, just that expectations weren't on the money.