Leeds signed the Germany defender from Freiburg in the summer in order to replace Ben White, who left the club following his loan spell last season.
Koch has slotted straight into the Leeds side and Dorigo admits that he expected the defender to be of great quality as he is a Germany international.
But the former Leeds defender feels the German has added an aerial threat that the Whites last had in both boxes when Jansson was at Elland Road.
Dorigo is also delighted at the way Koch has bounced back from a tricky start to the season and believes he has turned out to be an absolute bargain for Leeds at £13m.
The former Leeds star said on LUTV: “I love the aggression that he has shown as well.
“Of course he is a German international, we expect him to be absolute quality but coming into a Leeds side, alright how much he has to learn?
“For an attacking player it is a lot more, but for a defensive player, it is a bit easier and also as defenders, we love to play, and we are told to play in this Leeds side.
“And it is just the attacking threat, going back to Pontus Jansson and that I think is what he gave us especially and when he went, we missed that a little bit.
“We have got it back in spades I think.
“In our own box and the attacking box, he can attack the ball and any time a big striker is up against him, he relishes that.
“Taking into account, the two mistakes he made at Liverpool – unfortunate – and Fulham – that was a bit of a rash challenge – he has responded fantastically well.
“He looks an absolute snip at £13m.”
Liam Cooper’s injury problems mean Koch is yet to get a settled partner in the Leeds back four.