The 24-year-old Hartman made 21 Premier League appearances for Burnley this season, contributing five assists from left-back as the club were relegated to the Championship. His profile — a modern, attack-minded full-back capable of delivering consistently from wide — fits the role Romero occupied with distinction across two seasons on loan.
Loanee Carlos Romero was decisive for Espanyol throughout the campaign, including a goal in Sunday's 2-1 win at Osasuna that confirmed their La Liga survival. His return to Villarreal leaves a clear vacancy that Monchi must address before the season begins.
The Spanish sports newspaper Sport first reported the connection between Espanyol and Hartman. The left-back had already been spotted in the stands at the RCDE Stadium earlier this season as a guest of Burnley owner Alan Pace, a visit that generated initial speculation about a possible transfer given the shared ownership structure between the two clubs.
Hartman is valued at €18m according to Transfermarkt and previously played for Feyenoord before moving to England. His contract situation at Burnley, who will now compete in the second tier, adds a commercial logic to any deal — a player of his ability and age will want to remain in top-flight football.
Monchi, who arrived as Espanyol's sporting director after leaving AS Roma, has historically favoured identifying value-for-money signings in precisely this kind of situation — young, proven at a reasonable level, and available due to a club's change in circumstances.