I remember the heartburn over Big Al. It was legitimate... the feeling was that in 5 years, Big Al would be the better player, and probably for another 5+ years after that. Turns out Al has been very good but maybe not quite reached his ceiling as a player. But still, for ~5 seasons KG was the better player. For around a year now, that is no longer the case. Of course the problem with that thinking, is during that time KG was arguably the best player on a championship contending team, and almost nobody regrets having that window instead of a long term view of Big Al.
Gerald Green... maybe I'm working with hindsight here, but I think there were a lot more people in "the know" who saw him as a sell high opportunity, before he was labeled a bust.
As for Doc's comments, I think the point about the fans is clear if you take the whole thing in context. Boston fans show up to root for a last place team and fall in love with the young players. Most cities dwindle during the lean years, and only the hardcore fans really follow the prospects that closely. But as a whole, Boston is pretty darn special. There are not 5 fan bases on the planet that would stand and chant for their team in a playoff loss, aware that it might be goodbye. That's poignant stuff for a player/coach.