Great posts guys, well done.
I would like to elaborate on Martin's and Desmond's posts, that team tranquility stems from the front office, which Juve has been blessed with for many years. Luciano Moggi buys only the players we absolutely need. Therefore, not many players are "left out" of the procedings on the pitch, and this creates a cohesive team mentality, unlike a club such as Internazionale. With the Nerazzurri, players have been bought and sold; they come and go, to the extent which is excessively idiotic on the part of Moratti, first and foremost. Inter have repeatedly failed at bringing together a core unit of players, like the Ferrara's, Iuliano's, Conte's, Del Piero's, so they basically have no base roster. The only core players Inter still have are Javier Zanetti, Toldo, and Vieri. The management, though, goes ahead and makes questionable buys in the form of Veron, van der Meyde, Lamouchi, and Favalli, while they discard players such as Ronaldo (to an extent), Cannavaro, and Pirlo. How are players supposed to perform when they are not valued? Inter, as I see it, lacks a face; a mold, structural support. The only "face" I see is Moratti holding Facchetti in one hand and a money bag in the other.
As for Lazio, once again horrid management has taken its toll on a club which looked to have a bright future after 2000. But then the Mendietas and De La Pena's came about, and in turn so did the financial problems.
The key to success is a stable enviorment, which I am glad to say Juventus has one of the best in the game today.