The Brazilian joined the Baggies from Sporting Lisbon in the summer in a loan deal that will become permanent if the Baggies stump up £8.25million.
Pereira is now wowing Championship crowds having won the ‘rookie of the year’ award while playing for FC Nurnberg in the Bundesliga last season.
But why are Lisbon seemingly happy to let him go? And just how well did he do in Germany?
Here, we speak to Portuguese and German football experts to get their views.
The Portuguese perspective
We spoke with Tom Kundert, creator or PortuGOAL, and Alex Goncalves, creator of TugaScoutPT, to get their thoughts from his time at Sporting, and the deal which could see him join Albion permanently.
How highly rated is Matheus Pereira in Portugal and why?
TK: Very highly rated, especially among Sporting fans, most of whom cannot understand and are at varying degrees of furious about why he was never given a proper chance for Sporting's first team.
AG: He’s fairly highly regarded, there were very high hopes for him but ultimately he was never really given a substantial opportunity at Sporting, having only amassed 27 appearances for the club across all competitions in all his years affiliated with the club, his last appearance coming in May 2017 when he scored and assisted in a 4-1 win over Chaves.
That wasn’t enough to keep him in Sporting’s plans, and he then went out on loan to Chaves for the following campaign, where he really impressed, his excellent control and flair made him a real fan favourite across the season, adding so much attacking impetus to his side.
His seven goals and five assists across 27 league outings show some of his contribution from right wing to Chaves’ strong season, and he ended the campaign particularly strongly.
He was expected to go on and be given a chance for Sporting, but again he was sent out on loan, this time to Nurnberg.
So he did impress during his time in Portugal and proved himself to be an exciting player, but Sporting never really gave him a significant chance.
Having moved to the country at a young age and coming through the ranks at Sporting CP, why are the club seemingly willing to allow him to leave?
TK: That is a question that every Sporting fan is asking.
There have been some question marks about his attitude as he occasionally bemoaned his lack of opportunities on social media which although understandable, was not the best way to express his discontent with the situation.
However, he has frequently shown he has exceptional talent and having come to the club as a 12-year-old he does feel an affinity to it so it is mystifying why he has been constantly discarded.
The coach who started this season, Marcel Keizer, appeared very keen to give him a first-team role this time round but he was sold by the board above Keizer's head.
The upshot is most Sporting supporters and much of the press look at the departure of Matheus as evidence of the incompetence of the board, and not because of any shortfall on the part of the player.
AG: It was one of a number of decisions made by the Sporting board over the summer that was not universally approved by the Sporting fanbase, many of whom believed that he fully deserved a chance in their first team.
And considering the relative struggles of Sporting right now, to have a player with his technical ability would be incredibly useful.
But the board felt that he wasn’t needed, even though then-manager Marcel Keizer was giving him a chance over pre-season and obviously saw him as a viable option in his squad.
What do you make of the deal with West Brom, are you surprised about the amount Pereira is set to leave for if Albion and Sporting make the move permanent?
TK: See above. An absolute steal for WBA and a senseless decision by SCP.
AG: The price is, on the one hand, probably reasonable, what with him being 23-years old and the fact that Sporting clearly didn’t rate him all that highly and felt he might never fulfil his potential.
On the other, the fact that he had already had two successful loan spells and had done very well in a handful of showings for Sporting before that meant they were running the risk of getting undercut if he performed very well while at West Brom.
That’s the risk of allowing for an optional clause to make the deal permanent.
Benfica learnt that the hard way last season too, when they allowed Eintracht Frankfurt to have the option to sign Luka Jovic permanently for just a few million pounds – before going on to then sell him to Real Madrid for 60 million euros.
After doing so well at FC Nurnberg last season, is it surprising to see Sporting let him leave on loan once again?
TK: I can't speak about his spell in Germany because I did not see him, but his spell on loan the previous season at Portuguese top-flight club Chaves told you all you needed to know. He was outstanding.
AG: His departure did come as something of a surprise, as he was seemingly part of Marcel Keizer’s plans over pre-season, given a bit of game time in preparation for the new campaign, but the board felt he was surplus to requirements and let him go.
Somewhat understandable; he was 23 years old and hadn’t played competitively for the club since 2017. Time was clearly running out for him to fulfil his potential, and Sporting felt that he wouldn’t get suitable game time at the club, so allowed him to move to West Brom.
But again, considering his displays for both Chaves and Nurnberg while on loan, it only seemed fair that he was given a shot at the club he had been with since he was 14 years old.
Pereira has had a big impact in the Championship so far, would you say you've been surprised by this?
TK: No. I always felt it was just a question of making him feel wanted and his talent would do the rest.
AG: I don’t think anyone is too surprised to see him thriving in the Championship; he impressed in the Portuguese Primeira Liga with Chaves and, on several occasions, with Sporting, and he also did well in the German Bundesliga too.
There’s no doubting that he is an incredibly accomplished player, that’s why many Sporting fans were surprised and disappointed to see him leave yet again, but he has been particularly good for West Brom.
In terms of his position on the pitch, Pereira seems very capable on the wing but also in the number 10 position, was this the case in Portugal? And where do you think his best position is?
TK: At Chaves he did much of his best work in central areas. His skillset allows him to play both positions well, but perhaps a number 10 is preferable to make sure he is constantly involved.
AG: He’s always been a relatively versatile player, able to operate on both flanks and in that attacking midfield position just behind the striker, though was most frequently used on the right wing during his time in Portugal.
That was where he thrived the most, able to cut inside to use his favoured left foot.
Finally, should Albion secure promotion to the Premier League, do you feel Pereira has what it takes to make the step up and perform on one of the world's biggest stages?
TK: A tough one to answer.
In terms of pure talent, you have to say he's got a chance, but of course, to make it in such a high-profile league requires more than just talent.
I guess it will depend a lot on the quality of Albion's management/coaching. Sporting have a history of letting skilful wide players go for ludicrously low transfer fees given what they go on to achieve.
Exhibit one is Cristiano Ronaldo, but players like Ricardo Quaresma, Simão Sabrosa, even Nani arguably (although Sporting actually got a decent fee for him) were let go too soon and too cheaply.
It would not be a massive surprise to me if Matheus Pereira joins the list.
AG: I should think so, many players from abroad have been able to cope with that step up over the years, many with far less experience than Matheus Pereira has already picked up.
He’s not a young man anymore; by the end of the season, he will be 24 years of age, having had experienced in the Portuguese top flight, the German top flight and now the English Championship. Three very different leagues, and in all three he has performed to a very good standard.
He is well equipped to deal with the step up to the Premier League.
The German perspective
We spoke with Bryce Dunn from the Gegenpressing Bundesliga Podcast to get a take on Pereira's loan spell with Nurnberg last season.
We saw Pereira was out on-loan at Nurnberg last season, how did he get on in the Bundesliga?
BD: Pereira impressed in his time at Nurnberg.
As expected from a young talent coming to a new country it took a few months to get into his stride. The second half of the season he flourished scoring three and assisting two. Most notably scoring a pin-point strike from the edge of the box against reigning Bundesliga champions Bayern Munich.
Others may recall Matheus was involved in a red card four minutes into a game against Fortuna Dusseldorf for a low blow which was caught on VAR. But the positives significantly out weighed the negatives.
What's your opinion on Matheus Pereira judging from his performances for Nurnberg?
BD: He's demonstrated throughout his career to be an exciting player that has an eye for goal.
In the second half of the season he showed he's a threat while running at the opposition's defence especially on the counter attack as seen in his goal against Augsburg on Matchday 27.
Nurnberg had a difficult season as they were rooted to the bottom of the league and eventually relegated but their sporting director made the accurate description of Pereira's contributions saying in a Bundesliga interview, 'He gets us into positions in which we get good results'.
Based on his performances for the Bavarian club he indicated he will have a very bright future.
Where is his best position in your opinion, and why? He's done very well on the wing and in the number 10 position so far this season.
BD: With his preferred left foot, dangerous dribbling and acceleration he was often based on the right in an high attacking midfield position and I believe this was his strongest position.
It allowed him to use his pace while the team flooded forward on the counter. Also cutting in from the right wing makes him a goal threat.
In the past he's been compared to Mo Salah's style of play and just like the Egyptian a lone striker role would be less effective.
His drifting inside and dragging defenders out of position can also create space in the final third for his teammates.
Were you surprised to see Pereira head out on loan again this season?
BD: To be honest, yes I was.
Sporting are known to be a selling club. They bring youngsters in from around Portugal and South America at a young age (Pereira joined when only 14) and then selling on to make a profit and I wonder whether this loan move is an attempt to move him on and make some money.
Sporting finished third last season which is no shame when trying to compete with the likes of Benfica and Porto but I thought Pereira would have been the ideal player to add goals and assists when trying to close that nine point margin.
Sporting are currently sixth and I think they might be regretting this decision.
He's been quite a hit in the Championship this season, with Albion topping the table right now - did you feel he was of the quality to play in the higher leagues in England having seen him last season?
BD: Often the physicality and intensity of the Bundesliga and English leagues are seen to be similar in comparison and based on this then, yes I do.
He won Rookie (Young player) of the month in April in the Bundesliga, he featured in 19 league games starting 16, contributed to five goals and with a dribble success rate of 75% - All of this in a relegation battling side.
The stats looked good and it's been no surprise that things are going well for him especially when he's shown he isn't afraid to take on the challenge of a different country and league.
What do you make of his Premier League credentials, if Albion go up do you think he could cut it in the top flight?
BD: We all know that games and experience is what young players need to develop hence many pack their bags, leave the Premier League and head for the Bundesliga.
A combination of playing in second tier in Portugal, the German top flight and now the Championship all before the age of 24 seems like the perfect bases to be a Premier League success story.
Also didn't Cristiano Ronaldo play at Sporting as a youngster? Maybe I'm getting carried away but I doubt the step up will faze the young Brazilian.
Finally, what do you make of the reported £9m fee if Albion and Sporting make his move permanent? Do you think that's a fair price for him?
BD: Fair? I think it would be a potential bargain.
Currently his contract release clause is set at €60m which shows just how highly Sporting rate him. A cut price may be due to the Sporting failing to qualify for the Champions League this season.
With today's inflated market prices I feel West Brom would be foolish to let such a talent slip through their fingers and at the very least they would be able to make money on selling him on for more in the future.
Pereira comes from Belo Horizonte in South East Brazil, the same birthplace as Afonso Alves which had a dreadful time for Middlesborough ten years ago.
I'm confident Belo Horizonte is going to be the only thing in common for the two Brazilians as Matheus is a safe bet for the club and a player West Brom fans are right to get excited about.
You can follow Tom Kundert on Twitter here, Alex Goncalves can be found here. Meanwhile, you can keep track of Bryce's work with the Gegenpressing Podcast from the Futbolgrad Network here.