Grady Diangana completed a permanent switch to West Brom on Friday, a move which left West Ham captain Mark Noble "gutted, angry and sad".
Diangana, who made 21 appearances for West Ham in 2018-19 after breaking into the first team, spent last season on loan at West Brom.
He enjoyed a fruitful spell at the Hawthorns, scoring eight goals in 30 Championship appearances as the Baggies secured promotion to the Premier League.
The 22-year-old will now remain in the midlands, having completed a transfer for a reported fee of £18million.
However, it is a deal which experienced midfielder Noble does not agree with.
"As captain of this football club I'm gutted, angry and sad that Grady has left, great kid with a great future!!!!!" Noble tweeted in response to West Ham's announcement of Diangana's departure.
In their statement, West Ham explained the decision to sell the winger had been a "reluctant" one, yet they vowed that all funds generated from the transfer would be given to David Moyes in order to strengthen the Hammers' squad.
"The decision to sell Grady has been made reluctantly but - ultimately - in the best interests of the club and with the aim to strengthen the squad in different areas at this time," a statement on West Ham's official website read.
"The money received for Grady will be reinvested entirely in the team, in line with the manager's targets.
"We believe that this will give us the best possible chance of ensuring we have a balanced squad to compete in the Premier League and capable of reaching our objectives and ambitions this season."
Diangana spent a decade at West Ham, but he told West Brom's website he has no regrets over his decision to leave.
"West Ham was all I had known before last season and I’m sure people will understand that I felt some sadness at leaving," he said
"But coming here having had that season we have just experienced, there were no nerves about leaving at all. Knowing the manager and the players and the feelings I have got for the club just made me excited."