The 23-year-old Dutchman lasted just four games into a season-long loan before heading back down the M1 following the arrival of Bournemouth's Lee Camp.
His time at the Millers was error-strewn, with a number of costly gaffes contributing to the club's winless start to the season and despite original heavy backing from Evans, there was no way back for Roos.
However, Evans believes Roos will come good, but couldn't allow his development to come at the expense of results.
"People will question Kelle Roos going back," he said. "We as a management team 100 per believe Kelle Roos will play at a high level.
"But at this minute in time his inconsistency is not something we could afford."
The arrival of Northern Ireland international Camp should settle the nerves in the goalkeeping department, with Evans also seeming to have lost faith in Adam Collin.
Camp was an early target in the summer, but Evans is only too happy to revisit the deal.
"Obviously we were looking at the market place and approached back in the summer to sign Lee Camp but it was refused as Eddie was going about doing some business," said Evans.
"We kept tabs on it and we got indications early last week that Bournemouth might be prepared to move on and then Lee took his time to talk to two or three clubs in the Championship to decide where his future lay.
"We were over the line an hour or so before the deadline."
On Camp's qualities, Evans added: "I am delighted that we have been able to secure the services of such an experienced Championship goalkeeper.
“The lad played against the Millers on three occasions last season and our supporters will have seen it first hand the qualities he possesses.
"Lee had a number of options presented to him from other Championship clubs, but after much consideration he has decided that his future lies at the AESSEAL New York Stadium.
“I will add nothing else other than to say he now competes with Adam Collin to start in goal for Rotherham United. It goes without saying we all wish the lad every success.”
