Redknapp was hoping to sign the 26-year-old to help his side’s ambitions in the upcoming campaign. However, Badu eventually joined Turkish club Bursaspor on a season-long loan.
“It has been difficult. We had a vision of building a team that would really be competing this year to make the play-offs and be right bang there trying to challenge for promotion,” Redknapp told his club's website.
“At the moment we have found it very difficult, but it has not been through a lack of trying. I did a deal the other day for a lad from Udinese - Badu - a Ghanaian boy and top midfield player. I drove to Huddersfield to watch him play.
“It took me six-and-a-half hours to get to Huddersfield, met him after and then spoke to him two days ago and he gave me his word on the phone that he wanted to play for me.”
He added: “He is really a good player. His value is £6 million, and we were going to loan him for a year. I wake up the next morning and he has signed for a Turkish club!”
Badu spent seven seasons with Udinese after arriving from Berekum Arsenals in 2010. He was presented to the press by his new club on Thursday.