Feel this is a bit misleading, in Eriksens' case it's very much from where you ask him to defend. When playing attacking midfielder for the Danish national team, his work rate is sublime and doesn't shy away from tackles or tracking back and presses well, but when playing deeper as he's done in Italy he looks really out of position.
Well, Hareide, who thinks Eriksen is a fantastic player, also says that Eriksen is dependent on having a free role. If we are to sign Eriksen, we must have a system that compensates for his weaknesses. Personally, I think Ancelotti and Eriksen will be a perfect match.
On the other hand, Ancelotti will have a challenge with having both JR and Eriksen on the same team. Both are creative playmakers, but are not very mobile and like to get the ball on their feet.
None of them are very fond of running after the ball, and working hard defensively. Allan and AD can compensate defensively, but we need someone forward in the field who can give some dynamism, otherwise we become very static.