In the summer, supporters watched the West Midlands outfit cash in on the likes of Max Kilman and Pedro Neto, generating funds which could eventually reach in the region of £90m.
O'Neil's side went on to accumulate just three points from their opening 10 matches in the Premier League before recording successive victories over Southampton and Fulham.
Cunha played a key role in those two fixtures, contributing three goals and two assists in that double-header alone to put himself in contention to become the division's Player of the Month.
However, a scenario may now arise where Wolves have to fend off interest in his signature, a report indicating that there are plans to offer the 25-year-old a new contract.
"Zero concerns"
With Wolves having paid £44m for Cunha - who holds a contract until 2027 - when signing him from Atletico Madrid, it will realistically take in excess of £60m for the heads of the club's hierarchy to be turned.
Nevertheless, speaking at a press conference on Friday, O'Neil ruled out a sale in January, despite claiming that he wants Cunha to be wanted by "everyone in the world".
The Englishman told reporters: "Firstly, zero concerns from my part. I want him to play as well as possible, I want everyone in the world to want him. That is my job to help Matheus perform at the highest level.
"Mine and Matheus' relationship, and his understanding of what we are trying to do here is exceptionally good. I don't foresee there being any problems whatsoever in January.
"Contract-wise, I leave that to the club. We have a real focus, Matheus included, on tomorrow's game, and making sure that we are in the best shape to beat Bournemouth, and the contract stuff will be handled by the football club.
When pushed on if there is any possibility of Cunha leaving in January, he added: "Matheus won't leave in January. Definitely not."
Form player in the Premier League?
With seven goals and three assists from 12 matches this season, Cunha deserves to be regarded as one of the players of the season.
Four goals and three assists have been contributed from his last 360 minutes of football. Only Liverpool's Mohamed Salah (four goals, one assist) can rival Cunha over that period.
However, Salah has contributed a goal or assist in five successive games, with Cunha looking to match that feat versus Bournemouth on Saturday.