Rafa is mediocre, not bad, but he's nothing special.
I wouldn't blame him for the situation at Inter. After winning everything in the previous season there is always lack of motivation, players are tired, hence the players are more injury prone and Moratti is more thrifty nowadays.
Rafa Benitez isn't from the managers who can build a team with future, he has never developed a youth system, he just doesn't think in perspective. This is why he's destroyer. He just doesn't have an eye for being a great manager.
Ancelotti is the same though. Look Pep and Mourinho are the modern role models for managers.