Ronaldo missed 3 penalties (against Barca, Bayern, Chelsea) and scored 5 in CL semi finals & finals, almost 40% so your "law of averages" is not applicable here. The guy misses almost half the time when it matters most in CL SFs and finals and waits to be bailed out by his teammates or by rival team's players. Whether or not he was bailed out by others is irrelevant as he failed in his task of converting his penalty just like Messi in Copa or Baggio in WC. That others bailed him out just means that he was lucky (remember Terry's miss) unlike Baggio in WC or Messi in Copa who were not that lucky. He did not have the same luck against Middlesbrough last week, and tbh, looking at the way you are evaluating penalty misses, it should a “big deal” and source of embarrassment for Ronaldo (from your perspective) to lose to a team from a 2nd division with him missing the penalty in FA Cup (the only remaining winnable thing for United this year) and United going out., especially considering all the fuss surrounding his arrival at United for a new challenge.
I am only responding to this post due to the people making a big fuss of Messi's miss against Real for obvious reasons acting as if other top players never missed one in high-stake elimination games. I have seen Van Basten, Baggio, Zico, Maradona, Platini, Ramos, Kaka, Riquelme, Robben and many other top players missing them (Mbappe this year at EC) at their prime in very high stake WC, ECs CL games, so as a principle, try to stay away from criticizing them (like most normal football fans after the initial happiness or pain) for their miss as I know that there is a big luck factor involved in such situations and kind of feel sympathy towards them. Messi's miss was not even a tie ending miss, the game was the first leg of a 2nd round CL game and he had a good game overall creating most chances, couple of really clear chances for Mbappe. That does not mean that it was not an important miss (tbh it was kind of painful for me to watch it as I kind of knew he would miss it probably due to Courtois heroic saves earlier and his history with Real), of course it was important and Messi obviously failed in that task, but evaluating his overall game performance only focusing on this miss does not make any sense.
Also, disagree that Ronaldo played more big games than any other player when you have players like Muller, Xavi, Messi, Iniesta etc. who played in multiple WC, EC, Copa, Champions League, League Cup finals, El Classicos etc.