The Spanish coach left The Hawthorns 24 hours after the end of a dismal campaign where the Baggies finished one place above the Premier League relegation zone.
He lasted just four months, having been appointed following the sacking of predecessor Steve Clarke in mid-season.
Mel's struggles to communicate with the squad have been highlighted by McAuley, who also said that a member of the club's backroom staff was taking a key role in training at one point in Mel's time in charge.
"One of the big problems was that we had a computer analyst putting his boots on and coming on to the training pitch and trying to coach 20 professional footballers. He was trying to translate for Pepe there," said the Northern Ireland international.
"It was difficult for some players to take. The lads weren't having it all, to be honest.
"Language has been a big barrier. He'll tell you that himself. We had the frustration of we didn't understand completely what we were being asked to do."
West Brom won just three games under Mel's management, rounding off the season with a 2-1 defeat at home by Stoke.
"A big thing we've been missing is honesty around the place," McAuley added. "That brings distraction and means people go in a different direction. In a way we were lucky that there were three teams worse than us."