Yep. I'm still waiting for a good technical explanation of why this is. Bad footwook, is there a glare on his contacts, is he just crappy at judging vertical distances, bad technique? How do you get to be #1 in the world and can't put away probably 50% of overheads? What gives?
Your observation seems to be generally shared here: Novak can have very "rusty" and inefficient game when things do not "click" for him on a given day. Cerainly not as "graceful" as Roger's, especially in defeat.
However, I remember Novak can overcome those moments and turn around a crappy match into a win. I remember some 3-4 years back when he was on top, the first of his big matches against Stan in AO. He was visibly frustrated, blaming his shoes for his poor footwork, gesturing at his box to bring him shoe replacement (they did and it helped), blaming his contcts fog, etc. Very unprofessional behaviour, not to mention not worthy #1 player! Yet he overcame that emotional tantrum and came back winning that big match which is what is mostly remembered.
Not so now. He's likely to be better at the next tourney becase he loves the game and is physically capable but it's probably safe to say his mentalily is far less mature than that of the rest of big guys. Just like the worst side of Nick Kyrgios, only not directing his tantrums at the judges/audience but keeping it to himself and unable to relieve it, it destroys him from inside. Needless to say, the sporsors will turn away from such player and shower a "graceful" player like Roger with their money. Roger's endorsements were always far bigger than Novak's, even at the times when the latter was dominatng the game and Roger slumped into #3-4.
Tennis is a stressful sport on the top and you must learn how deal with the stress on court, Novak definitely has to improve on it, provided he's not to old for the improvement required.