Piroe has joined West Ham on a season-long loan that will become permanent next summer if the Hammers win promotion back to the Premier League, their target after relegation last term. Neither club has confirmed the fee, though it is understood to be worth close to £12m to Leeds should the obligation to buy be triggered.
The 27-year-old scored 73 times in the Championship across four seasons, first at Swansea City before his 2023 move to Elland Road, where he finished as the club's top scorer during their title-winning 2024-25 campaign. He could not repeat that form in the Premier League last term, going 16 appearances without a goal.
"I think it's a good opportunity for me to show what I've learned and how I've grown as a football player over the years," Piroe told West Ham United's official website.
Born in the Netherlands but capped internationally by Suriname, Piroe came through PSV Eindhoven's academy, had a loan spell at Sparta Rotterdam, and only turned prolific once he crossed to English football with Swansea. He becomes West Ham's fifth permanent addition of the summer, following Keiber Lamadrid, Joel Veltman, Manor Solomon and Arne Engels through the door at the London Stadium.
Bornauw's departure completes a swifter turnaround. The Belgium international, who arrived from VfL Wolfsburg only last summer, returns to the Bundesliga on a season-long loan carrying an option to buy reported at between €4m and €5m. He made just 12 Premier League appearances, five of them starts, as he struggled to displace Leeds' first-choice central defenders under Farke.
Hamburg SV sporting director Claus Costa said the 27-year-old fits the club's profile exactly.
"Sebastiaan fits our requirement profile perfectly. He brings the physical presence, duel strength and heading ability we want in our defence," Costa said.
"On top of that, he has a mature and consistent style of play. Sebastiaan is a player with real leadership qualities, someone who takes responsibility on and off the pitch and can organise a defence."
Bornauw previously spent six years in the Bundesliga with 1. FC Köln and Wolfsburg, making well over 100 league appearances before his switch to Yorkshire. Leeds paid around £5m to sign him last summer and are already lining up a replacement, with a deal for Borussia Mönchengladbach's Nico Elvedi close to completion.
Both exits, confirmed within hours of one another, reflect a busy summer of squad turnover at Elland Road as Farke reshapes his options for a first season back in the Premier League.