I'm just going off what my Celtic season ticket-holding friends and family say about the various managers they have had during my time in Glasgow, which just about goes back to the managers I have mentioned. Its a fair point about the 'biscuit tin' times, although they were still better off in terms of being able to attract players than all bar one other club up here, just for a bit of perspective.
The other thing about Barnes' tenure at Celtic Park is that Henrik Larsson had that really bad injury. Most teams would struggle when losing their talisman like that. Even Dalglish at Ewood suffered from a slump in results when Newell and then Shearer got injured in 91/2 and 92/3. I think Celtic fans came to realise just how important King Henrik was to them over the following few seasons.