I wish i had an easy way of conveying the kind of concepts that make an editor good, but i unfortunately don't. You're looking at this the wrong way.
"Flow" doesn't make an editor good. What CoD editors normally mean (or should mean with flow) is: having the editing down to a point where the editing is pleasant to look at. This is done by making sure that the cuts are correct in terms of (mainly) the direction of the movement, speed and relation to the previous clip. Here is an example of that kind of flow: https://www.youtube.com/watch?v=_egY2w5B7fA
If you were to ask a professional editor what he believed flow to mean, he would probably say something like: making it so that the video has an engaging progression. Here is an example of this kind of flow: https://www.youtube.com/watch?v=LfV_QjhqIjU
A CoD editor isn't really just an editor actually. A CoD editor does the recording, the cinematography, the directing, the sound design, the color grading, coming up with the concept, the vfx and AND the editing. The thing is, pretty much nobody is good at all of those things, and only a few are good at 3 or 4 of them. If you're looking at "top editors", and you only see them having "good syncing", chances are that they are not actually that good.
This guy: https://www.youtube.com/watch?v=_egY2w5B7fA is not that good.
This guy: https://www.youtube.com/watch?v=gCL1OPAFWhk is not that good.
This guy: https://www.youtube.com/watch?v=m7ath84LDqY is not that good.
This guy: https://www.youtube.com/watch?v=FtTXafdLYbA is not that good.
This guy: https://www.youtube.com/watch?v=uhFtnRS5qDI is good.
This guy: https://www.youtube.com/watch?v=WgcS1XwGPlQ is good.
I must admit that i have a hard time getting into the mindset of someone who might not be too experienced. This sounds very vain, but hey, it's the truth. The most important thing that make you a good editor is that you are creative. This doesn't mean that you use the best rap song or that you have "beast flow", but it does mean that you have a mindset that makes you want to figure out new ways to be progressive and fresh with new ideas.