To be fair, they had an immense injury crisis all the way through the first half of the season. But the issue with Klopp is his signings, I haven't been impressed with his signings for a while at Dortmund.
That's a bit harsh. It's mainly Immobile who stands out as an expensive flop and a few of his signings who failed to perform in his last season at Dortmund but look excellent now.
For the 14/15 season: Immobile, Kampl, Ramos, Ginter, Kagawa, Sahin
Immobile was a flop, Kampl was sold on after 6months with a 1m loss, not that big of deal. Ramos is a decent back-up striker, Ginter & Kagawa look great signings at the moment and signing Sahin on the cheap after he looked excellent during the loan from Real is still a good deal.
For 13/14: Mhkitaryan, Aubameyang, Sokratis and Jojic
The first 3 look fantastic right now and are key players. Jojic was bought for 2m and sold for 3m.
For 12/13: Reus, Schieber, Bittencourt
Schieber was underwhelming, no doubt. But he was cheap. Bittencourt went for about the same money he cost. And Reus was of course a brilliant signing for 17m Euro.
Going further back, it gets better and better. It all looked rather underwhelming last season, when the whole team sucked. Mhkitaryan looked like an expensive flop, Ginter was useless, Kampl a waste of space and Immobile a disaster. But right now, is it really that bad? Immobile was that one big mistake, but the whole team right now is full of his signings. Mhkitaryan, Aubameyang, Sokratis, Ginter, Kagawa and Sahin are 6 players you could call regular starters if fit and all were signed in Klopp's last two seasons.