Gustavo Poyet thinks it was bizarre for Chelsea to make no January signings and then announce a deal for Hakim Ziyech days later.
Frank Lampard's side confirmed in February that Ajax star Ziyech would be moving to Stamford Bridge after the 2019-20 season for a fee that could reach €44 million (A$74 million).
While Poyet believes the Morocco star could prove an exciting addition to the Premier League, the former Chelsea midfielder could not understand why the move was announced so soon after the club failed to make any signings during the transfer window.
A transfer embargo prevented Chelsea from bringing in fresh faces before the start of the season but, despite Lampard stressing the need for reinforcements, no new players were signed once the ban was lifted at the start of January.
When asked for his opinion on Ziyech, Poyet, who spent four years with Chelsea and won the FA Cup, Cup Winners' Cup and UEFA Super Cup, said: "A very good player, very interesting player."
He continued: "I didn't understand – and I'm not criticising anyone – why Chelsea, after all that went on in the summer, not being able to sign players, get to January with the possibility of signing players, they didn't, and then three days later, four days later, they announce they sign a player for next year. It's not normal, okay?
"I'm not saying it's bad, but I lost it a little bit because you complain a lot about not being able to buy, then you have the chance to buy and you don't, and then when the transfer window is closed you announce that you bought one.
"Leaving that aside, I think they got the quality of a player the fans will enjoy watching.
"Obviously, there's going to be a period of adaptation, and it all depends on where you came from, your character, and how they can perform, but if he adapts himself to the strength and power of the Premier League, I think he's going to be a player you're going to go and enjoy watching play.
"Plenty of skill, technically gifted, can score goals, and he can produce things for the team."