There's been rumors circulating for a few weeks now that Napoli were on the edge of wrapping up a transfer deal well in advance of the window opening. Most people were assuming that Aurelio De Laurentiis and Rafa Benitez were looking at Javier Mascherano and Maxime Gonalons, as those two have been "close to signing" for almost a year.
Now, though, it sounds as though the truth was in an entirely different direction:
Stef Wijnats is a fairly well-respected Belgian sports journalist who makes regular appearances on both radio and TV sports shows in Belgium. It sounds as though this particular tidbit was said by him on the radio in the last couple of hours or so, and it sounds as though he's very confident in this news.
As for the deal itself, Kalidou Koulibaly is a 22-year-old French central defender considered to be one of the brighter defense prospects coming out of France in recent years. This is his second season with Belgian club KRC Genk, and after an impressive debut campaign, he's been much more up-and-down in his form this season. He's been virtually ever-present for Genk this season, though, missing only five matches, four of which were due to an injury in December.
Koulibaly is tall (6'4") and very strongly built. He's not a burner speed-wise like his countryman Kurt Zouma, but he's quick enough thanks to a healthy dose of athleticism. He's not a standout with the ball at his feet, but he's good enough so as to avoid major concern in that area. Personally, I regard Koulibaly as a defender with a very good future ahead of him.
That said... if this reported fee of "more than €8 million" is true, Napoli paid too much. Koulibaly is still pretty raw and that's a lot of money for a player who has only been OK in Europa League play and has yet to actually dominate on a regular basis at a level well below Serie A.
He would certainly give Napoli a more physical presence in the middle, which is something they've very much needed at times this season. I don't think he's a clear-cut upgrade over Federico Fernandez, though, which is what Napoli really needs along the back line right now. If Koulibaly really is coming to Naples, it almost certainly means that Miguel Britos is on his way out this summer.
If and when we get more information for you on this potential deal (and any other potential Napoli transfers, of course), we'll bring it to you. In the meantime, the report should probably be taken with some salt, though less than most other transfer rumors this time of year.