Ralf has a 1.65 points per game in the league since taking over, which is an improvement over Ole's 1.41 before he got fired this season. It's better than Mourinho's 1.61 the season he got fired. Just below Moyes 1.67 (with a team that was the defending champion), and LVG's 1.73 in his second season.
Is it good enough? Of course not. But people are going overboard talking about him as if he is by far the worst of them all, considering that he walked into by far the worst situation out of any of them. Obviously the last 6-7 weeks has been a shit show (although still better than what we were doing under Ole), but before that he'd done a decent job stabilising the ship. It should also be noted that recently he's had about 9 players out who would all have been expected to start a significant amount of matches at the start of the season.
If he is making strong recommendations behinds the scenes that the board are listening to, then it'll end up being well worth it IMO. Obviously we would have hoped that he would have got top 4, but the most important thing for me was always that he'd provide a proper review of the football side of the club by a person with experience in doing so.