During the last half of this season, I have noticed a very significant change in both Chandler and Ross' behaviors.
What I mean is that Chandler has become a bit of a "Ross" if you will. Acting more mature, responsible, capable of holding on to a relationship. And Ross is well "Chandler", who has immatured, especially after he started dating Elizabeth (Ugh!!), and is acting like a complete dork. I know, he's always been a dork, but this time, it's more annoying that usual.
When I watched last night's episode, where Ross and Joey are complaining about Chandler's attitude towards them, it really donned on me, especially when Joey told Ross that they were the new Joey and Chandler, that Ross has become the new Chandler and Joey loves it. I think we'll see those two develop a friendship the way Chandler and Joey have. (eg. watching Jasmine Bleech on Baywatch. :)).