Ramsdale joins Sheffield United for a reported £18.5m, with the 22-year-old signing a four-year contract at Bramall Lane three years after he left the club to join the Cherries.
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The move comes after Henderson posted a farewell message on his Instagram after two seasons on loan at Sheffield United.
Henderson returns to parent club Manchester United, and is set to challenge David de Gea for the No 1 role after impressing during his loan spell.
"I would like to take this opportunity to thank everyone at Sheffield United for the last two years. Winning promotion to the Premier League with my brothers and having the season we had this season is something I will never forget," Henderson said.
"I would like to thank the manager, my team-mates, the backroom staff and of course, the fans, who have been unbelievable towards to me. I will look back at the last two years as an important chapter in my career and more than anything, I’m grateful to have had the opportunity to learn and develop with such a class group of lads.
"I can’t wait for the next chapter! Once again, thank you for everything! Once a blade, always a blade!"
Henderson or De Gea?
De Gea endured another difficult season in goal for Manchester United, with a number of high-profile errors costing the club points – notably in the draw against Tottenham in June and defeat to Watford in December.
Henderson meanwhile shone for Sheffield United upon their return to the Premier League, keeping as many clean sheets (13) as De Gea and making one more save (97 to 96).
Overall Henderson conceded fewer league goals (33) than De Gea (36), and had a better save success % of 74.62 to 72.73.
Close statistics, undoubtedly, but that only makes Henderson’s numbers all the more impressive given he was playing for a newly-promoted side, albeit on that finished an impressive ninth.
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