Now that we know for sure that Adil Rami and Keisuke Honda have joined Milan to reinforce a side that has had an atrocious domestic season, let's see which player would be the best signing hypothetically.
Taking a look at Milan's deficiencies, you could make a case that the best signing they could make would be a world-class central defender to pair up with Adil Rami.
The full-backs are good enough—Ignazio Abate and Mattia De Sciglio will fill the two spots on the flank. As we've learned through the years, a team doesn't need world-class full-backs to win a Champions League.
After all, the Rossoneri managed to hoist the fabled trophy with the likes of Massimo Oddo and Marek Jankulovski suiting up on both defensive flanks.
All they need now is a true, quality centre-back. Christian Zapata has had his moments, but is way too inconsistent and panics in possession when he's getting pressed.
Philippe Mexes, on the other hand, is a ticking time bomb who is always one boneheaded foul away from being sent off. On top of that, he has looked out of shape and just isn't the type of Milan-class defender the team needs to compete at the next level.
Here's where Rami comes in. The hulking Frenchman is looking to recreate himself after his career at Valencia ended on a sour note. He was a pillar on the French national team and his biggest strength is Milan's most glaring weakness—aerial defending.
The perfect partner for the giant would be a quicker, more technical defender in the mold of Thiago Silva. Since that player is out of the question because of the lavish finances behind it, Atletico Madrid centre-back Miranda would be the perfect January transfer window purchase for the club.
Miranda has exploded on the scene with Atletico this season, leading the back line to first place in La Liga and showing a ton of class both in possession and with his anticipatory instincts. His composure is second to none in La Liga and he has formed one of Europe's finest partnerships with the bigger Diego Godin.
This could translate well at the San Siro, where Miranda could form a similar partnership with Rami. Considering Milan spent €12 million on Alessandro Matri, it would be a shame not to snap up a player like Miranda if he cost around €15 million.