It didn't dawn upon them to give him a wage raise + new release clause two seasons ago?
they knew the player for a very long time (since he was 16 or something) and so they surely did not think "hey, one day nuri will wake up and play like zidane"... they probably were surprised by nuris performances themselves (or at least surprised how the performances influenced others to believe nuri was world class) and just did the most smart thing they could in selling him to real madrid for the most they could get (given the clause).
dortmund now have reinforced their midfield and people say its even more creative and unpredictable after sahin is gone. so no marks of "oh god, a world class player left us". its more like they made him look good and now they got money out of it without actually missing him much.
just like certain teams make certain players in them look good while they would completely fail at other clubs.
if nuri actually was worldclass than you would have seen that way before, because he played professional games with a pretty young age and was visible to anyone with a tv, but guess what no one said "hey that young guy that plays for feyenord has glimpes of world class, lets sign him" similar to that nuri even played games for the second squad of dortmund in the 4th german league ... even there no other club of an higher league said "look how he plays... he is totally above the other players of this league, lets snap him up".
just because you get bought by real madrid does not make you world class
Hmm - we'll if Bundesliga watchers think he's crap then maybe he's too risky
Do opposition teams fear him when he's on?
no one fears him because he does not even have a "name" here. he is not even established as standard bundesliga player... and surely not mentioned when someone talks about young talented players