Except Tosun would never have been allowed to leave if there was no other cover available in the squad for the CF. As it was, Tosun could not be used as a wide forward at all whereas King can... and we NEEDED Tosun to go out on loan, in a last ditch attempt to get some sort of fee back for him. In fact, I'd say the only way the King purchase can truly be said to be a failure is if we don't manage to punt Tosun away this summer for between £5m and £10m.
Add to that the fact that at the time we KNEW Tosun was incapable of contributing any further to our campaign (he's proved repeatedly that he offers nothing), whereas King at least has a track record of moderate sucess in the Prem. Tosun's best season ever in English football is only marginally better than King's worst season ever.
I agree that it's frustrating that King hasn't scored or made an assist since he's arrived. But let's not pretend Tosun was any good.