Manchester United recovered from going a goal behind to extend their unbeaten run in the Premier League to four games and left the south coast with all three points after a late Marcus Rashford strike completed the comeback.
"I would like to answer that but it is hard for me to answer", he said.
"Defensively very bad, absolutely terrible".
"In that situation, after nearly going 1-0 down after a couple of minutes, that triggered instability in the team". And I feel really frustrated with that.
Epitomised by his block in front of Marcus Rashford in the second half, the Dutch worldwide stuck to his task well all afternoon, and couldn't quite intercept Pogba's cross to Rashford for the decisive goal of the game.
Acuchillan a dos personas en el edificio de Sony Music en Londres
Cuando salía del edificio vio a un trabajador de Sony llorando y a la Policía irrumpiendo en el edificio por las escaleras. Sony Music dijo que "dos trabajadores del equipo de banquetes estuvieron involucrados en un altercado violento".
"I was happy bringing Ander Herrera into the game", declared Mourinho. "He was fundamental for us". 'But in the best teams you need more than that.
Rashford, himself, was axed from the starting line-up at the Vitality Stadium but staked his place for regular inclusion with a dramatic stoppage time victor and Ferdinand believes his all-round game marks him out as a better option than Lukaku to lead the line.
"When he is now much closer to becoming a top player, obviously I would like him to stay".
In Lukaku's absence, Marcus Rashford, who turned 21 on Wednesday, came off the bench to score a stoppage time victor against Bournemouth. No matter how many minutes to the end of the game, we have the feeling that anything can happen. Bournemouth must have thought they would come away with at least a point, especially after Jesse Lingard missed a chance just before the end, but United kept coming - as they have recently under Mourinho, even if the engine sometimes stalls along the way. "And that is a fantastic quality for the team".
United face the Serie A champions on Wednesday and Mourinho can not be certain whether the Belgium striker will be ready to travel. "We don't know, a muscle problem, and we have to wait a little bit".
"He needs these couple of days".
Bournemouth manager Eddie Howe insists that is a matter for Southgate but praised his player's contribution. When I say defensively I just don't look to the defenders.
"For the goal, Lewis Cook has done really well to pick out the pass".