Richarlison is the poster boy for the Hornets' work on that continent. An £11.2million gamble when he signed from Fluminense in 2017, the forward became a Brazilian international and Premier League star before completing a switch to Everton which could eventually be worth £50million.
But he is far from alone.
Watford have similarly high hopes for João Pedro, the Brazilian teen signed from under the noses of Barcelona and Liverpool in January. Ditto Luis Suárez – no, not him – and Cucho Hernández, both of whom have shone on loan in LaLiga this season. There was even a time when Adalberto Peñaranda, a star at the 2017 Under-20 World Cup, was touted as a £50million prospect.
Who is Pervis Estupiñán?
It's in LaLiga where another gem dug up by the Pozzo family's extensive scouting network resides. Estupiñán is coming to the halfway point of a highly successful two-season loan spell at Osasuna where he has attracted interest from some of Europe's biggest clubs.
On paper at least, the full-back will remain with his current club this summer. But Watford hold an option to recall the defender too. With such an illustrious list of suitors, he could be flipped at a huge profit without playing so much as a minute for the Hornets.
What are Estupiñán's strengths?
Osasuna were only promoted last season, along with Estupiñán's previous side Mallorca. But they find themselves 11th, in little danger of being relegated back to the Segunda División. Estupiñán has flourished in a side whose commitment to attack has seen them average the sixth most on-target shots (4) per 90 this season.
Estupiñán is the perfect fit for Jagoba Arrasate's side – a gung-ho full-back who likes to rampage up and down the left. In fact, if we look at Osasuna's average position map we can see Estupiñán gets high and wide while the rest of the midfield and attack play very narrow.
Given the freedom of the left to maraud, it's no surprise 43 per cent of Osasuna's attacks come down that flank with Estupiñán integral to their game plan.
A prolific dribbler, Estupiñán ranks third in LaLiga for completed take-ons by a left-back (per 90) with 1.89. He is second for attempted dribbles (3.37) behind only Real Madrid‘s Ferland Mendy (3.6).
Unlike plenty of modern full-backs there is an all-important end product to his game. He carves out 1.3 chances per 90 (third in LaLiga at left-back) and an average of 0.11 assists is enough to secure his place in the top ten. An accurate and reliable crosser, Estupiñán connects with 1.26 deliveries per 90 – enough to rank fifth in LaLiga against his peers.
It's at this point you might be expecting us to gloss over Estupiñán's defensive work. But he's actually a better defender than must attack-minded full-backs.
It's difficult to read too much into unweighted defensive metrics because teams in Osasuna's position have less of the ball than Barcelona or Real Madrid. Making more tackles than Jordi Alba or Marcelo, then, is no surprise.
What is interesting, though, is Estupiñán comes out on top among LaLiga left-backs for interceptions with 1.82 (per 90) which points a strong ability to read the game and time his interventions.
Equally, the number of tackles made by a player is more of a reflection of how busy they are. However, using true tackle win rate (total tackles/total tackles + challenges lost + fouls from attempted tackles), Estupiñán comes out with a very impressive 63.7 per cent.
What are Estupiñán's weaknesses?
For a relatively inexperienced player, there aren't many blots on Estupiñán's copybook. However, his decision-making must improve if he is to fulfil his potential.
No-one in the entire of LaLiga has lost possession on more occasions (551) than Estupiñán this season. Per 90 minutes he ranks 11th but it's still not great.
However, there's an element of inevitability given his role within this Osasuna side. In the entire Osasuna squad, only midfielder Fran Mérida (76.1) has more touches per 90 than Estupiñán (73.76). On that basis, the Ecuadorian international is more likely to lose possession on a regular basis than his team-mates. Still, he could pick his moments better when passing or dribbling.
What next for Estupiñán?
With José Holebas out of contract at Watford this summer, it's anticipated there'll be a vacancy at left-back. However, Gino Pozzo – the club's owner – is a shrewd operator. It's hard to imagine him turning down big money for a player with 29 top-flight appearances to his name.
The Manchester Evening News claims that despite reported interest from United, the club aren't looking for a left-back. Between Luke Shaw and young deputy Brandon Williams, the position is covered.
However, Chelsea and Tottenham both need left-back upgrades. The Blues are expected to sell either Marcos Alonso or Emerson Palmieri this summer but have Leicester City's Ben Chilwell in their sights. As for Spurs, Danny Rose is expected to leave but a more senior replacement seems likely.
Which leaves Spain. Estupiñán has spent the last five seasons on loan at Granada, Almería and Mallorca, gradually working his way up the ladder. Barça boss Quique Setién is unconvinced by Jordi Alba's current understudy – Junior Firpo – and Estupiñán could be the ideal long-term heir.