If true, it's an odd purchase.
On his day, he is still a legit playmaker.
On the other hand, he doesn't seem like what our midfield needs if we're spending big on a lone CM. We get bossed around in midfield pretty frequently. There seems to be some opinion out there that he's a better defender than what one would think (which belies what my eyes told me when he was across the park), but statistically it's pretty clear that you can bully him. We already get bullied centrally with regularity.
It seems to me that we need another defensively-oriented box-to-box player, so that injuries don't render us soft at the back, and that we can get creativity from the flanks and perhaps James or Sigurdsson playing centrally.
Ancelotti may be looking at the same dataset and thinking he needs another playmaker to keep opposing defenses honest and make them stay home, and there may be merit to the argument that we need more consistent service centrally on the counterattack. Certainly, a lack of goals is more the problem than concessions, though we need to tighten down as well if CL, rather than Europa, is the goal.