From the above link: "There’s enough evidence to suggest that Doucoure is more or less an average PL player that has an inflated reputation that can be attributed to his goal scoring. "
Ok so Doucoure is a Sigurdsson replacement, a player whose strength is scoring goals but only scores half as much him. Personally, I wouldn't sign him due to lack of fit.
In short, yes.
He's a.totally different type of player, but the two things current sigurdsson currently adds to this side are : lots of pressing and runs into the box.
They are doucoures two stand out abilities as a box to box midfielder.
The other is that he has that Ross Barkley style ability to take the ball from one box to the other by charging up the pitch with it.
The difference is that outside of that he's an OK midfielder who can do a little bit of everything else.
Be fine if we can match that with another actual midfielder who can do other good stuff.
Functions of a midfielder :
Tackles in each third
Pressing / off the ball defence
Rotate the ball
Break the lines with passes
Drive the ball forward with dribbles
Off the ball attacking runs
Prolly some other stuff
Finding a blend of players who do a bit of that each to form a whole is the key.