Bonucci headlines the five biggest transfers in Serie A this summer

The transfer window has barely been open for two weeks but already some significant names have changed clubs -- especially in Italy. With that in mind, we asked Michael Cox to asses the five most significant transfers in Serie A so far.

Leonardo Bonucci, Juventus to Milan

This is unquestionably the most significant move of the European transfer window so far. Bonucci is probably Europe's best ball-playing centre-back, quite possibly the best centre-back in Europe full stop. His decision to leave Juventus after six consecutive Scudettos would have been a huge blow regardless of his destination, but moving to Milan feels particularly significant.

Milan, after all, have been in the Serie A wilderness recently, with finishes of eighth, 10th, seventh and sixth in the past four seasons. But with new owner Li Yonghong ploughing serious money into the club, new arrivals like Andre Silva, Ricardo Rodriguez, Mateo Musacchio and Hakan Calhanoglu providing genuine excitement and coach Vincenzo Montella among the most promising in Italy, Milan are now a force to be reckoned with once again.

This almost feels like revenge for Juventus snatching Andrea Pirlo away from them in 2011, with the regista's arrival in Turin, combined with the appointment of Antonio Conte and the move to the new stadium prompting Juve's modern period of dominance. Indeed, just as Max Allegri overlooked Pirlo's brilliance toward the end of his spell at Milan, his relationship souring with Bonucci seems to be the primary reason Juve have lost one of their most dependable performers.

Curiously, it's arguable that since Pirlo's departure, Bonucci has been the Juventus player who has replicated his role. Although clearly playing in a different position, Bonucci's booming long diagonals have helped to compensate for the absence of Pirlo pulling the strings from deep in midfield. Six years after that transfer, Milan may have found a technical leader who can dictate their play.

Borja Valero, Fiorentina to Inter

If Valero played in any other position, or was any other nationality, he would be a regular at the international level. But there never has been a worse time to be a Spanish passing midfielder, and therefore Valero has earned only one cap -- now six years ago. In Italy, however, his playmaking qualities are very much revered.

Upon his move from Villarreal to Fiorentina five years ago, Valero made an instant impression, dictating the Viola's play from an increasingly advanced midfield role, and being voted into Serie A's Team of the Season in his debut campaign. Since then he has been admirably consistent, and became the most popular Fiorentina player for his off-field antics, constantly posting selfies of him enjoying Florence with his family.

But with the Della Valle family falling out with supporters and seemingly desperate to sell the club, Fiorentina's prized asset was allowed to leave. "I don't think I was as important to [Fiorentina's directors] as Florence has always been to me."

Fiorentina's loss is Inter's gain. With the talented but hugely frustrating Ever Banega returning to Sevilla after a year away, Valero now feels like Inter's key midfielder. With the likes of Marcelo Brozovic and Geoffrey Kondogbia providing the defensive security and energy, Valero should be allowed the freedom to slalom forward into attack and create chances.

Now 32, Valero has been waiting his whole career for a chance at a big club like Inter. Now is his time to shine.

Douglas Costa, Bayern Munich to Juventus

As a general rule, Italian clubs don't really do wingers particularly well. Yes, there have been the odd exceptions down the years, but generally Italian sides play narrow in midfield, rely on width from full-back, or push players out of position to the flanks.

Juventus' run to the Champions League final, with right-back Dani Alves on the right of midfield and centre-forward Mario Mandzukic deployed wide left rather summarized Italian coaches' distrust of natural speedy wingers -- although that shape worked perfectly well for Juventus for most of the campaign. Even Juan Cuadrado often felt like a converted wing-back rather than a true winger.

Costa, though, is the purest winger around. He can't play at full-back, he'd be uncomfortable up front, he doesn't have the guile to play as a No. 10 for a top club and he'd managed only four goals a season for the past four league seasons. In an era of multidimensional attackers, there's a lot he can't do.

But wide left or wide right, Costa stretches the play, goes down the outside and whips in devilish crosses. And at this simple, almost old-fashioned skill, Costa might well be the best player in Europe. Few full-backs can cope with his incredible acceleration, and in Italy full-backs simply don't come up against that type of threat regularly. With Mandzukic and Gonzalo Higuain waiting for crosses in the middle, Costa could prove one of Serie A's star players next season.

Josip Ilicic, Fiorentina to Atalanta

Another classy playmaker jumping ship from Fiorentina sees Ilicic moving north to join Atalanta, having previously seemed set for a transfer to Sampdoria.

Atalanta might suit Ilicic well. They're a club who have often got the best from talented, slightly misunderstood Italian playmakers -- Cristiano Doni, Domenico Morfeo, Giacomo Bonaventura -- and will be prepared to tear up last season's template and construct a side around Ilicic's talents.

Although primarily an assister, on his day Ilicic can be a major goal-scoring threat. Few Serie A players boast such an explosive left foot. The Slovenian isn't a world-beater, but in the right situation he's capable of dominating his side and running the game. He's in the Gylfi Sigurdsson mould, a player who seems more suited to a midtable club with the entire side based around him, rather than playing for a Champions League challenger where consistency is expected every week.

That said, Ilicic also thrived at Palermo when playing in the same side as another playmaker, Javier Pastore. If he can strike up a similar relationship with another Argentine, Alejandro Gomez, Atalanta could be one of Serie A's surprise packages.

Antonio Cassano, Sampdoria to Verona

For nearly two decades, Antonio Cassano has been among the most entertaining players in Italian football. The absurdly talented, ludicrously lazy and entirely undisciplined creative forward has enjoyed a nomadic career taking in Bari, Roma, Real Madrid, Sampdoria, AC Milan, Inter, Parma, Sampdoria again -- and now joins Verona. After turning 35 last week, this might be Cassano's final chance to remind everyone of his quality.

A switch to Verona, one of Serie A's more romantic clubs, seems to suit Cassano well in itself -- but the most exciting thing is that Cassano will be linking up with his old pal Giampaolo Pazzini, whom he played alongside at Sampdoria. Their partnership was perhaps the most devastating Serie A has witnessed in recent years, with Cassano playing as an inside-left, drifting inside onto his right foot, and Pazzini playing up front and making clever runs while acting as a traditional target man too. They took Sampdoria to fourth place in 2009-10, and turned the side into among the most exciting in Italy.

Seven years on, it remains to be seen whether Cassano and Pazzini still boast the requisite quality. Pazzini banged in 23 goals last season, finishing as Serie B's top goal scorer, but the step up to Italy's top division is significant. Cassano, meanwhile, lacks some of his old mobility but still boasts tremendous vision and guile, and is perhaps the closest thing to a true Italian genius in this post-Totti world. Cassano is always unpredictable, but there's a chance he'll give us one final flourish.