How many watched Dier, Alli, Lamela or Son?
Just because people haven't watched them play doesn't mean they won't be a success.
Look at Ronaldo.. No one had really heard of him, Sir Alex and co had done the leg work in scouting and it paid off.
Not saying it will be the same at all but football transfers are about gambles.
I think that's why Poch is very militant with the mentality bit, I bet there are loads of strikers with enough ability to play second string to Kane, but they also need to have the right mindset to push Kane and work incredibly hard for a starting place. Sign to train and all that.