Angry -- but with whom?

Mishnah 5:14 of Pirkei Avot talks of people being classified into four types of temperament:

(i)  The person who is easily angered but easily placated—his reward is offset by his loss. 

(ii) The person whom it is hard to anger but hard to placate—his loss is offset by his reward.

(iii)  The person whom it is hard to anger but easy to placate is a chassid, a pious person.

(iv)  The person whom it is easy to anger but hard to placate is wicked.

The Mishnah is usually assumed to be referring to a person who gets angry with other people. The plain text does not demand that this be so. Sometimes a person gets angry with God, and sometimes with himself. Does this Mishnah apply equally to these scenarios? 

In principle there is no reason why it should not. If anger is a corrosive and damaging emotion, it will adversely affect the well-being of the person who feels it regardless of the cause of that anger.  However, there is a difference. However much anyone rages against God, there is absolutely no way that this anger, or the person who feels it, can do to hurt or harm Him. When angry with oneself, any damage done is counterproductive since the object and the subject of the rage are one and the time. It is only when anger is directed against fellow humans that it can lead to the sort of destructive and vengeful action that can undermine the social basis of human civilization.