Thanks for the comment, Bob.
Even though I have mostly taught people to always include phrases on both ends, many times it is redundant. Here is a list of the corresponding phrases for the model above:
R1: kicks, is kicked by
R2: bounds, is bound by
R3: coaches, is coached by
R4: penalizes, is penalized by
Keep in mind that an association has a single meaning. For example, an incorrect association between referee and player would include phrases.
R4: penalizes, yells at
The penalize association and the yells association are actually two different relationships.
The moral? Look closely at models and see if you are being good by placing phrases at both ends, but maybe you are mixing two different associations with one link… which leads to bugs!