They are Need Achievement Theory, Attribution Theory, and Achievement Goal Theory. Need achievement theory is an interactional view that considers both personal and situational factors as important predictors of behavior. Personality factors component of need achievement theory states that each of us had two underlying achievement motives. One is the capacity to take pride and satisfaction in our accomplishments while at the same time trying to avoid experiencing shame or humiliation as a result of failure. For Greg, his behavior will be influenced by the balance of these two motives.
High achievers enjoy evaluating their success and low achievers attempt to avoid failure.
Greg's desire to avoid failure thereby suffering the shame and humiliation, could be the reason he under-achieves on the field. Situational influences require considering the probability for success in the situation or task and the incentive value of success. The probability for success depends on whom you compete against and the difficulty of the task. If Greg is a low achiever, he would not see the actual competition as a challenge so the value he places on being successful would not be very high. Some low achievers such as Greg may also fear success so subconsciously perform at a lower level in order to avoid success as much as to avoid failure.