Vergara forced his way into the Napoli first team from January onwards, impressing with his goals and performances to the point where he is now considered too important to sell. Approaches from outside have been firmly rejected.
Cesc Fàbregas and Como are known admirers, and the interest from Tottenham and AS Roma has been genuine, but Napoli's hierarchy has made clear that Vergara is not available at any realistic price.
Allegri's track record with young players is seen as an encouraging sign for the midfielder. The Livorno-born coach has a history of elevating technically gifted youth into key first-team roles — Matias Soulé and Kenan Yildiz being the most cited examples from his time at Juventus, where he also gave significant opportunities to Dean Huijsen and Davide Bartesaghi at a young age.
For Vergara, who has confirmed his quality in a short burst of appearances since the turn of the year, the coming season represents the chance to prove himself over a full campaign at the highest level. Allegri's style of play and his willingness to back technical players gives the midfielder every reason to believe he will be central to Napoli's plans.
Any club looking to revisit their interest in the summer or in January will find the same answer from Naples — he is not for sale.
Vergara's story over the past six months has been one of the more compelling in Serie A — a player who was barely in the conversation at the start of the year and has since become a transfer target for clubs at the top of England and Italy. That kind of trajectory is exactly what Allegri has shown he can sustain and build upon when the right player is given the right environment.
Napoli's decision to resist the offers and keep faith with a homegrown talent as they transition to a new coaching era speaks to both the club's financial position and their belief in what the player can become over a full season.