The Hammers had been linked with the Sporting Lisbon midfielder for weeks but missed out on his signature before the transfer window slammed shut.
That left supporters and Bilic upset with the manager admitting he thought the deal was all but done.
Bilic says he has been trying to fill the deep lying defensive midfield position with a quality player since arriving in East London back in 2015.
And he even conceded he had to offload the likes of Sofiane Feghouli, Ashley Fletcher and Robert Snodgrass to raise the necessary funds for Carvalho.
But it seems the Sporting Lisbon man was not the only Euro 2016 winner he thought he had signed to join international teammate Jose Fonte at the club.
And Bilic revealed on Sky Sports he thought he had both players in the bag.
“I wanted Carvalho. We all did. We are a bit thin and I took that risk deliberately," Bilic told Sky Sports.
“It wasn’t only Carvalho, it was also Andre Gomes, who also looked done."
The news will be a bitter disappointment for Hammers fans who, despite watching their team grind out a first win of the season over Huddersfield on Monday night, remain unconvinced about the direction the team is heading.
A lack of a discerning style or identity in the last year has been divisive.
But Carvalho and Gomes would have been perfect players to build one around.
Perhaps all is not lost, though, and the players may yet strut their stuff at the London Stadium come what January... or next May.