This is a bit of a sitrep.
We are nearing the end of a long project where I am comparing the relative fortunes of Fairport Convention and Fleetwood Mac in the 1970s.
Of the two groups, only this one had a “transitional” stage. With both bands, there had been a pair of game-changing events in 1970. Details of these are given above, but in essence were like this. Firstly, Peter Green quit Fleetwood Mac and Sandy Denny and Ashley Hutchings left Fairport Convention. Then at the end of the year, Richard Thompson departed from Fairport Convention and Jeremy Spencer deserted from Fleetwood Mac.
One thing common to both groups, of course, was their complex history of personnel changes. However, their respective paths in the 1970s differed greatly. Fairport Convention basically staggered from one crisis to the next, producing much splendid music in the process. Conversely, Fleetwood Mac spent five years searching for themselves, again producing some brilliant (and quite a lot of mediocre) stuff. At the end of that period, they reinvented themselves in a unique way. Thus, the five years can be seen as “transitional”.