While a lot of people here are focussing on the performances of our top order, I think another difference between now and the Fleming era is the abilities of our lower order. When you think about it, Fleming's top 6 really weren't significantly better than the lot that are playing now (with the notable exception of Richardson). Fleming, Astle, McMillan, Vincent, Sinclair and Styris all averaged in the 35-40 range, and whoever was tasked with opening with Richardson was always a walking wicket.
However, compare our lower order in the late 90's of Cairns at 7, Parore at 8, Nash at 9 and Vettori at 10, with van Wyk, Bracewell, Boult and Patel. In the Fleming era we had one of the strongest lower orders in world cricket, and could rely on them to get us from 150/5 to 300, if at least one of the top 6 was there to support them. Nowadays, especially as Vettori's batting has fallen away in the last year, we can't bank on making more than 50 runs after the 5th wicket falls, and that's a serious problem.
Anyway, we're realistically on par with Bangladesh at the moment, and I'd expect them to smoke us on current form, the next time we tour there.