What qualifies these people as experts?
Silly things like actually playing professional basketball, coaching it or spending massive amounts of time around the sport and it's athletes. Y'know, nonsense like that.
Most of them are journalists. Journalists are basically fans who get paid to watch games. Don't think they are experts any more than the people on this blog. Former players are different.
You're wrong about the journalists thing. The job of a journalist, particularly one who focuses tightly on something like the NBA, is to develop a deeper and broader base of knowledge and understanding (therefore "expert"). This should not upset people. I mean - sure, Charles Barkley puts in no effort but we don't really watch Charles for his expertise. And Simmons clearly knows the game but his heart makes him say things that seem silly sometime.
But guys like, to pick at random, Kevin Arnovitz or writers like, Jackie MacMullan - they know waaaay more than the average poster on this message board. Again - not an insult.
I think the pro's benefit from a broader knowledge of the league, but, without question, there are quite a few posters here who know the Celtics much better than the pro's do, and understand the game just as well. Consequently, I value the insights of many posters on this blog more than the pro experts.
I'd guess that most of the experts would view the center position as a large advantage to the Cavs, when those who have "scouted" the Celtics as well as we have might see that as more of a wash, for example. Rondo/TA can keep Mo Williams' scoring in check, but most national writers probably don't know that. Jamison seems like a major addition for the Cavs, and he is, but against KG, Jamison is no quicker while giving up a height advantage to KG. But the national people don't watch as closely, and consequently don't respect what the C's really can do.