Mean

The usefulness of reward and uselessness of punishment can be explained quite cleanly, as well as why it is so difficult to convince those who don't believe it.

Coach sees a young player make a brilliant move, praises him. Next time player tries it, he fails - because this is a new skill, and a certain amount of luck is involved in getting it exactly right. Coach thinks it's because he lavished praise. Really, it's regression to the mean. Praise continued will eventually improve performance because the player understands better what is expected, but not immediately.

Coach sees a player screw up royally, shouts at him. Next time player tries it, does a lot better, can't really do much worse. Coach thinks it's because he shouted and player knows better than to mess up so badly. Really, it's regression to the mean. Continued punishment will demoralize the player.

This relates to the post from yesterday. The military is all about shouting at failure to punish it, and giving praise only in extreme success (often after death.) No reason to get much better, so the mean only improves a bit due to simple practice. But it does get to a base level of competence, which would happen anyway. The attitude within this system, over years, is to keep one's ability down, get away with whatever can be snuck by the shouters, and not get caught.