The Trinidad & Tobago midfielder told The Journal: "He says things sometimes but it just happens for the best.
"People question whether the manager is the right man, whether he is picking the right team. So he has a right to blow fire when things are not going well.
"I remember it only once, last season at Sheffield Wednesday. Anyone who was there knows we were dominant and took our chances. Then we went 2-0 up and at the end it was like, 'What is going on?' He had a right to do that."
Sunderland won the Hillsborough match 4-2 but Keane was furious his players made a game of it, allowing the Owls to pull the score back to 3-2 until Edwards finally put it beyond doubt in the 89th minute.
Keane hopes to make some signings in the New Year and, despite being arguably the 36-year-old's best signing, Edwards is in under no illusions his place is under threat if he does not perform in the interim.
"It's his job (to make signings) and he wants the best for the club," Edwards argued. "His job is not easy. He has to make some players unhappy and some happy. It's his job to get the best team and give fans something to cheer about. He is doing a good job so far. The table says otherwise but it's not that we are playing bad football.
"Losing is nowhere near his vocabulary. You could probably count on one hand how many times he lost as a player. We all have a winning mentality but sometimes you come away having lost and there is little you can do about it."