Let me describe Real Madrid and Ronaldo's UCL winning campaigns:
2013/14:
Played weak teams in the form of schalke (and Dortmund (who finished 21 pts behind Bayern) in Rd 16 and qf but Real and Ronaldo got the job done.
In the semi fair enough the won against a good side. But Guardiola's Barcs tactics in the absence of Barca type players was found out; a high line plus wide central defenders without players with the same technical ability against a counter attacking side was fatal. As for Ronaldo, he scored twice: the first was purely due Bale's selflessness and Ronaldo making sure he was the chief beneficiary. His second was a good free kick, credit where its due. Other than that, his performance wasn't really memorable.
As for the final, Real were lucky in the end to win it and Ronaldo was probably the worst player on yhe pitch.
2015/16:
Ronaldo was good against Roma in q16 both legs. Roma themselves missed a dozen sitters in both legs. Hardly dominant from Real but so typical of them in the ucl.
In the quarter finals, Real and Ronaldo were poor in the first leg vs a very poor Wolfsburg side. In the second leg, Real turned it around courtesy of a hattrick from Ronaldo that was as jammy as can be. Other than that, his and Real Madrid's performance was nothing to write home about.
In the semi, Ronaldo was anonymous vs a city side that wasn't really great. And ofcourse, if he doesn't score, you forget he is on the pitch.
In the final, again Real were saved by a last minute goal by Ramos. Ronaldo himself was quite poor.
2016/17:
This one I give you. Both Ronaldo and Real Madrid deserved to win and Ronaldo's goals were the most important reason for the ucl win. The only lucky game for Madrid was vs Bayern. By this time, Ronaldo had perfected the art of poaching.
2017/18:
Other than that game in Turin, Ronaldo wasn't great (despite his goals vs psg in R16)and actually was terrible in the semis and the final. Perhaps the worst player on the pitch.
In summary Real Madrids UCL wins had significant luck, significant goals from Ronaldo/Benzema/Bale/Ramos and a few good performances.
They often rode luck or depended on someone to score a last minute goals to win the competition and yhe same was true last season.
On the contrary other teams like ourselves in 2008, Barcelona, Bayern were the best teams in their ucl winning seasons.