I was just posting re. the Black Crowes and it made me think about something that I have come to realize more and more lately: to get a truly great band going, you need to have every position manned by the best. In other words, you can not coast on eg a red-hot guitarrist, but try to slip through the detectors with an average Bassist. You might sell some records, or draw a crowd, but I don't think you can really become one of the greats. Obviously you need other things too, but my point is that even if those are in place I think it takes a another Allstar Band to get on top. Sometimes adding one crucial player to the mix puts a band over the top, or viceversa; losing one can destroy them. The Who lost Moon and it was never the same. Clash found Topper headon and it made the difference. The Crowes pieced this totally awesome band together. Ford, Gorman, Colt and especially the keyboard man made all the diffrence.
I saw Lucinda Williams with Doug Pettibone and without and there was a completely different aura co,ming from stage.
There are countless examples.

"...no longer shall you trudge 'cross my peaceful mind."