Coates has already invested in the squad by completing swoops for Senegal striker Mame Biram Diouf, Slovakian youngster Dionatan Tiexeira as well as experienced Premier League campaigners Phil Bardsley and Steve Sidwell.
Stoke have been long-term admirers of Diouf, who scored eight goals in an injury-hit season for Hannover last term, and Coates revealed manager Mark Hughes was determined to snap up the former Manchester United man.
"Well, he is one that Mark liked really early on, and we did try to sign him on a couple of other previous occasions," Coates told the club's official website.
"I guess you could say it was third time lucky for us because we managed to get the deal over the line this time, having gone close to acquiring him twice before.
"Of course, in this day and age there is no such thing as a free transfer, but it was certainly more favourable to us to conclude this deal without having to pay a transfer fee for him. That was a bonus for us.
"We are all hoping that he will maintain the form he displayed during his time with Hannover and make a real impression here in the Premier League. We certainly feel he is capable of doing that."
Although Coates is delighted with his early progress in the transfer window, he is keen for more additions before the start of next season.
He explained: "We are happy with what we have done so far, but I don’t envisage that being the end of it. I think there will still be a few more ins and outs."
Hughes led Stoke to ninth place in the Premier League last season, their finish since returning to the top flight.
