With all their offensive mids they really don't need Salah at all - and it really does look like they're signing him just so we can't.
Either that or Chelsea are doing what all big clubs do, buying up all the hottest prospects, training them up to be worldies and then selling them on for profit or after a series of loan spells they can slot right in to the first team when they're at the top of their game ie Lukaku.
Salah is a well known youngster, who pretty much topped the Don Balor list of top young players at the end of last year, so Chelsea will be well aware of who he is.