Alex Neil says the desire of Chris Maxwell to be a No.1 goalkeeper was the driving force behind his move from Preston to Charlton.
The Welshman has joined the Addicks on loan for the rest of the season.
North End manager Neil said: “We had two keepers in Declan Rudd and Maxi and there’s not a lot between them.
“Declan has been playing and Maxi is the type of lad who, if he is not playing, wants to be playing.
“There has been very good competition between the two of them but we have got to the stage now where Maxi, for the future of his career, wants to make sure he is a regular No.1.
“That was something we couldn’t guarantee.
“It is nip and tuck between them and Maxi wants to be somewhere where he knows he is going to play.”
Last season, Maxwell played 30 Championship games, all but two of those up to the end of January.
He had been first choice from September 2016 until then, a run of 67 league games.
Rudd got the nod for much of the second half of last term and started this season as first choice.
“We have had these two guys competing for the best part of a year-and-a-half.
“It’s not uncommon that at some stage one of those guys is going to think, ‘You know what, this is not for me, I want to be playing regularly’.
“My argument to that would be if someone performs to the top level they will make themselves the No.1.
“Both Declan and Maxi have had moments when they have performed very well, and moments when they could have done a bit better.
“Hence they have been switched around.
“If you look back, Maxi was in the team until Ipswich when he was sent off.
“That naturally changed the situation, Declan came in for the Bristol City game which we won and he kept a clean sheet.”