Need to dig out the threads from around the time when he left, but my memory of it all is that:
a) we'd switched from 3-5-2 to 3-4-3, he wasn't as effective as a wide forward, but it was a necessary tactical switch for the good of the overall squad that he was the unfortunate loser from (with Traore the opposite, a big beneficiary)
b) after a strong start his general form had plateaued (particularly in the second half of his final season here), there was a sense that his ceiling wasn't as high as we'd initially thought, so even if £45m would turn out low it shouldn't be by that much in the long term
c) it wasn't just £45m, we were also getting a youth prospect with a decent rep thrown in with Hoever
Of course all three of those turned out to be mistaken impressions (and how), but I don't remember a huge amount of gnashing and wailing about him being stolen before his time when he left. More that, as much as it would've been nice to keep him, we'd have to accept growing pains like it as part of the process of the team maturing into the PL.