There have also undoubtedly been times when he's looked like he's enjoying his football again. The five-time Ballon d'Or winner may have been held scoreless in his first two competitive outings for Al-Nassr, but he was named the Saudi Pro League's Player of the Month for February after scoring eight times in just four fixtures.
With on rounds remaining, he's managed 14 goals in 19 matches, which is not too shabby, even if five of those strikes came from the penalty spot.
There have also been flashes of the old turn of pace that used to leave defenders trailing in his wake, and even a goal from a free-kick.
Of course, at other times, he's looked like exactly what he is: an ageing superstar struggling to connect with colleagues of inferior quality. "I swear to God," former Al-Nassr star Fahd Al-Huraifi wrote on Twitter, "I did not want Cristiano to come to the Al-Nassr while we still had Talisca, because if both players say 'Give me the ball to score', it's a disaster.
"I love Ronaldo very much, I love his professionalism and respect, all of which are indisputable but... he is no longer able to dribble or rely on himself. He always wants an assist."
Of course, that is precisely the kind of striker Ronaldo has had to become in order to prolong his incredible career. But it's also why agent Jorge Mendes was unable to find any elite European club for his former client last summer, leading to their bitter "divorce".
Ronaldo believes he can still score goals at the very highest level - and why wouldn't he, given everything he's achieved in his career? But fellow United legend Eric Cantona is among those who feel that Ronaldo is struggling to accept that he no longer deserves to be a starter wherever he plays - which is what Erik ten Hag quickly concluded at Old Trafford earlier this season.
"There are two types of veterans: those who want to play every game because they still think they’re 25 and those who realise they’re not 25 and are here to help young players, they know they won’t play every game, but they’re aware that they’ll have their moment," the Frenchman told calciomercato.com.
"There are players who help new players: [Zlatan] Ibrahimovic still does it with Milan, or [technical director] Paolo Maldini when he was a player at Milan. Ronaldo doesn’t realise he’s not 25 years old. He’s already older and doesn’t know that, instead of being unhappy about not having played all the time, he should accept the situation."
Ronaldo appears unsuited to such a role, though. As he admitted himself, he struggled to get through the younger players during his second stint at United, thought that arguably says more about them than Ronaldo.