Castellanos, 26, joined West Ham United from Lazio in January for around £25.5m, with the move framed at the time as a significant acquisition for a club still hoping to avoid relegation. The timing looked ambitious — West Ham were already deep in trouble — and the anticipated impact never materialised. He managed two goals and one assist in eleven appearances, with the club's relegation fight ultimately unsuccessful.
Italian journalist Marco Mampreso reported Fulham's interest, identifying the Cottagers as a club looking to add a proven striker in the event that they retain their Premier League status under a settled management structure. Incoming manager — or continued manager, depending on the outcome of Marco Silva's contract negotiations — would inherit Castellanos as a target if the deal could be structured affordably.
The Fulham connection matters because it keeps the player in the Premier League, which Castellanos is understood to prioritise given his desire to rebuild his reputation at the top level. The West Ham situation has been damaging on several fronts simultaneously — the club's relegation removes one obstacle to a sale, but also reduces any potential transfer value.
The deeper complication is Lionel Scaloni's decision to leave him out of Argentina's World Cup squad. Castellanos had joined West Ham partly with the tournament in mind, believing a move to England would give him the visibility and form to force his way into the reckoning. The failure on both fronts — sporting and national team — leaves him in an uncomfortable position entering a summer that will require significant decisions about his career trajectory.
Brazilian club Flamengo remain a long-standing admirer and have tracked his situation for months. A move to South America would represent a significant step backward in footballing terms but may be the most realistic option if a Premier League deal cannot be concluded quickly.
West Ham's expected player sales this summer will be driven by financial necessity following relegation. Castellanos is one of the club's highest earners relative to his contribution and is likely to be among the first assets made available to interested parties.