Zaha quietly put together a very good season this year - maybe his best or certainly his second best in his time in the Premier League. You can see his evolution towards the be all and end all for Palace - he scored more than ever this year but assisted less than ever.
He's also 29 soon, somewhat pace dependent and relies on teams allowing big spaces on the transition (typically better teams than Palace) to find gaps to attack. He may find that somewhat harder at a Spurs when teams camp, though I doubt that issue rears it's head much if playing for Everton. Everton certainly isn't the big career leap he seems to be referring to when he's talking about moving for the right opportunity. I'm not sure that Spurs is either now.
£40m isn't a terrible price, you're getting a consistent double figures 10+ G+A winger who knows the league and is undoubtedly effective. His age and changing systems might not help him, I think Spurs style wise would suit him better than Everton. He's not a player that transforms your club though, unless you're at about the same level as Palace. Like Kane, like Grealish, he took a massive contract at the wrong time in his career and has been priced out of a good career move by a club desperate to hang on to them. Unlike the above two, I'm not quite sure Zaha is the real deal, or he would have put together a couple of big, big seasons by now.
