Interesting what you're saying about perhaps Nole trying to not be the joker and perhaps being too serious and trying too hard to be the serious pro and it might be hurting his game a bit - not just the pressure of trying to get to #2 and then #1 but to do it in a "statesmanlike" manner. Federer and Nadal have had a lot of good press for their conduct in rivalry in the past few years - I wouldn't be surprised if that's something Nole would like said about him - and I suspect the stuff in Monte Carlo about his retirement might have hurt his feelings a fair bit.
Maybe he's trying too hard to be seen in the same way as those two guys rather than letting it happen naturally as a consequence of his results and his comportment on court and off it?
Another thing - he's always been, you know, complimentary and nice to his opponents at the net when he wins or loses, which is nice, but sometimes he almost seems to be too nice - like with Safin at Wimbledon it was almost "thank you for beating me" - if you know what I mean
Could be coming from the same place - the desire to be seen as a great sportsman, which I think these days he largely is anyway.
Thing is, if he's trying too hard and not having fun on the court, not enjoying his tennis, that's no good either. When Murray was with Brad Gilbert he wasn't having fun anymore on court, putting too much pressure on himself and the results were patchy and then the wrist injury happened. He needed to get back to enjoying his tennis while striving for the results, getting the right balance. Perhaps things are just a bit out of balance for Nole right now.
He is a very smart guy though, and he learns very very fast, so I don't expect him to take very long making any adjustments that are needed.