First off, I do not reject the premise that some players handle pressure moments better than others. I completely agree that some people are chokers. I just don't think you find those at the Major League level. They are weeded out before they reach the Major League, or if they get there, they don't last very long. I think we long ago agreed in the idea of clutch as the ability not to choke. In that sense, my opinion is that all Major League players are clutch.
What I reject is the idea that clutch is a repeatable skill or that there is any predictability to it.
There is no data that supports those first two propositions. At the same time, there is no data that refutes them. With the idea of clutch, there is overwhelmingly strong evidence against it. If the stat people start conducting studies on the impact of managers to their teams psychologically and determine that it's a bunch of hogwash, I will change my opinion on the matter.