“Sunk cost assumes rationality?” Not really sure what you mean by this. The economic phenomenon to which I was referring, The Sunk Cost Fallacy, is used to describe a type of highly irrational decision-making into which people regularly fall. When a stockbroker buys stock in an underperforming company, then continues to buy stock because he thinks he’s invested too much to pull out, that’s an example of the Sunk Cost Fallacy, and also an irrational action. I agree that it may be asking too much of some sports commentators to them think about such things, though. I’m happy to see that Kevin O’Connor, at least, seems to be taking a similar line of thought on the trade.