Yes but by the same rule you are supporting unpredictability, you are missing the essence of the point that he is by nature, unpredictable. Which means he can be very hit and miss, as you never quite know what you are going to get. That is the obvious positive aspect of unpredictability, but then equally obviously, it must also have an opposing negative aspect too.
If i can sum up my thoughts, then it would be that both Valencia and Bale have a more simple role to fulfill. They beat their man for pace and put in a quality ball. You may know exactly what they are going to bring, but because their main attribute is so easily replicated, that makes it a very reliable and consistently effective contribution.
Nani plays differently, his game is more spontaneous and instinctive than theirs. He has obvious capabilities they do not, but in football is not easy to consistently reproduce the more difficult and higher risk skills.
We see all the time that it is often the most simple and easily repeatable methods performed well, that are often the most regularly effective. Bale and Valencia are predictable, but they are still very difficult to stop. Which means we can often depend on their predictable contributions, moreso than a less predictable, though more talented Nani or a Giggs.
As a striker you need some predictability to have any confidence in what your winger will regularly provide. If you never know when or how your winger is going to do anything in particular, how can you make the right runs and find space at the right time, if you don't know what's coming next?
This is why Rooney seems to enjoy playing so much with Valencia, because he knows what to expect far more often than not, and he can plan his decisions on the basis of that assurance.