I tend to agree. A human being is not a pair of dice. If someone comes back from injuries, for instance, he may play poorly. If someone on the other hand is having a great year, they may have improved confidence or simply hit their stride and play better. The thing is, what is this study determining as a cluster? A single game or a single season? Because its not uncommon at all to have great seasons followed by poor seasons. I don't think its a case of 'hot hands', but human beings are affected by a large number of variables so its only natural to assume the stats they produce are non-random.