Those people who criticize Ronaldo, they don't know football at all. If Ronaldo stays a longer time in Man United, he may retire very soon. Also, he will never have the chance to join Saudi league. It was surely a very brilliant decision to leave Man United earlier. We can see that Man United never showed a good progress. Staying in Man United just ruins Ronaldo's career!!
Don't know how to interpret it but yes, with Ronaldo the Al-Nassr ended up on third place in the Saudi Professional League, while the winner was Al Ittihad and the runner-up was Al-Hilal. On the other hand, Man United hasn't been performing well and they are in the 15th spot in the Premier League.
Although it is never that we blame or appreciate any single player for the success or the failure of the league but i think it would be much easier for Ronaldo to get success in the Al-Nassr league as compared to the premier league where the competition is of next level. You need to be young and energetic to perform well.