The forward signed for the London club from Club Brugge for £30m in July 2024.
Over the midpoint of the season, Brentford are in fantasy land.
With four wins in five games, and a Brazilian striker scoring the goals, suddenly supporters are dreaming of thoughts of trips to European capitals next season.
A convincing three-nil win over the Black Cats moved Keith Andrews' side into fifth in the Premier League – a place that was good enough to secure Champions League football last season.
Only table-toppers the Gunners have gathered more points over the past half-dozen matches.
There's a significant distance to go yet but the West London outfit are firmly in the fight for continental football.
Few was predicting this last summer.
Thomas Frank had departed for Tottenham after a seven-year stint in charge, a period in which he had not only got the club to the Premier League but also established them in the top flight.
Club captain Christian Norgaard left for the North London club and goal-scoring duo two key forwards – who scored a total of thirty-nine goals in the previous campaign – were out the door, joining Manchester United and Newcastle respectively.
Set-piece coach Keith Andrews was promoted to succeed the Dane, while there was no striker among the off-season arrivals.
A season of difficulty, possibly even the drop, was widely predicted. Yet here we are in the new year with Brentford in the top five.
So, what is behind their success?
Brentford's decision not to bring in another striker was partly down to timing, with Wissa's move not going through until deadline day.
But they also knew they had a £30m striker already waiting to go.
The 24-year-old joined from Belgium in July 2024 for a then club record fee, but was hindered by fitness issues in his debut campaign, going without a goal in eight appearances.
The 24-year-old has gone about compensating for lost time this season, though, with his double against the Wearside club taking him to 16 league goals – the highest tally by a player from Brazil in a single Premier League campaign.
Given the countrymen who have come before him, that is a remarkable feat, especially with seventeen matches left to play.
"He has been a breath of fresh air," former Liverpool midfielder an analyst said. "He is physically intimidating, fast, strong, but technically better than people think. Good with his feet, either foot, he can score off both. You can see he's brimming with confidence. His statistics are incredible. He must be so proud. That's a big compliment to him."
That only a trio of global superstars have scored more in any of Europe's top five leagues to this point underscores the standard he is operating at.
And it is not just the volume but the crucial nature of the goals that have been so important for Brentford.
His first goal against the opposition was his 7th opener of the season. Given how often we are told the importance of the first goal in a game, having someone you can rely on to take that first big chance cannot be underestimated.
Prior to the game against Sunderland, no player to have attempted at least thirty efforts this season has a better shooting accuracy than Igor Thiago's 59.1%.
He finds the target. Do that often enough and the goals will – and have – come.
Given the hardships he had earlier in life, where he worked as a bricklayer to support his family following the death of his father, perhaps it should be unsurprising that pressure on the pitch is something he takes in his stride.
"Our scouts deserve a lot of credit for the type of players they bring in and characters," the manager said. "It is really impressive. He is a really unique person who has fitted into life very well. He has had to earn this path. He has worked for his journey and grafted. He has got serious grit about his personality. He is developing his abilities constantly and we are learning more and more about him. He is a largely complete centre-forward."
Their star striker is the headline act but the team are not and have never been a single-player team.
While they had key individuals – Ivan Toney, Christian Eriksen, Mbeumo and Wissa – under Frank, they were always seen as a team more effective than the individual components.
The fear was that once the Dane left, that may not be the case, and that the collective quality of their parts alone might not be enough to stay up.
As a result, appointing Andrews, with a blank managerial CV, and just a twelve months at the club was seen by those outside the club as a huge risk.
A maiden role is a challenge for anyone, let alone when it comes in the Premier League and having made the leap from set-piece coach to the top job.
But given that Ipswich boss Kieran McKenna was the only other option that Brentford looked at, they were clearly convinced they had the correct candidate.
To date, as often seems to be the case with the brains trust at the club, it looks as if they were vindicated.
Andrews won just a single of his first 5 league games in charge but big home victories against United, the Reds and Newcastle have followed.
Wins that, following their excellent recent run, could prove increasingly important in the race for Europe.
"We're in fine fettle and playing really well. We are playing with bravery and conviction in everything we do with or without the ball," he added. "We're happy with how we are going but we want to keep pushing."
In a league where the European spots and the lower mid-table are currently separated by just a handful of points, they have little choice, because things could rapidly look very different.
But, for now, The Bees are beating the odds. And the longer that lasts, the closer to reality those aspirations of the continent will become.