Keane explains loan exits for Sunderland pair
"But the opportunity arose and I think when one player is going out, it's ideal if you can send two young players out together.
"That's certainly something we look at doing, even when we are bringing players. I spoke to Chesterfield and we know they're a good club with a good manager.
"It was a tough one for us, because we've not got the biggest reserve squad, but it was an opportunity for them to get some league experience under their belt. And, as much as we appreciate the toughness of reserve football, you cannot beat that experience of first-team football.
"We sent them out together because it makes the adjustment easier if you've got someone in the same boat as yourself. I think we saw the benefit of that ourselves when Danny Simpson and Jonny Evans arrived as a pair on loan from Manchester United last year.
"The fact that you've got someone with you who is going through the same experience makes it easier for you to settle, I think."