Problem I had with the arguments against clutch, besides the definition of what's a clutch situation, is that they use a players BA in and out of clutch situations to make the determination. I haven't seen a comparison against the league norms in those same situations.
The stats have shown that a players BA doesn't change much in or out of a clutch situation. What they haven't shown (or I haven't seen anyway) is how that rates against everyone else. What is the comparison of the league BA in and out of a clutch situation? If the league BA during a clutch situation shows a 15 point drop, and Mazeroski stays around the same, or only drops 5 points, then you could say there is an indicator he is clutch. THat would define clutch as more of a non-choke.
It the league BA stays the same, or is higher, then that an indicator against it.
Defining what is a clutch situation, being able to gather the data for those situations, and comparing that against a baseline is whats needed. IMO the articles I've seen so far have not make the case.