A point was all Spurs needed to seal their qualification into the last 32 and while goals from Gareth Bale, Son Heung-min and Dele Alli secured progress with a game to spare, the visitors were not at their best in Austria.
LASK dominated the first half and caused problems throughout, with the away side's back-up goalkeeper Joe Hart at fault for two of the goals.
Asked what he learnt at the Linzer Stadion, Mourinho insisted: "Nothing new really.
"The fact that the Europa League group phase doesn't motivate some of the players, I knew it.
"That some players are fundamental for us and I always need on the pitch in any circumstance, a couple of these players to give a little bit of balance to the team.
"As an example, (Pierre-Emile) Hojbjerg and Sonny, without them I don't think we would have a positive result. Nothing really that I learn. The players know and I share my feelings with them, I am normally right.
"When I saw the warm-up before the game I had a feeling and I told the players before the game that there was a huge difference in intensity, communication and enthusiasm in their warm-up and our warm-up because I was looking at both. Nothing surprises me."
Spurs were without Harry Kane due to an unspecified injury, but Mourinho was able to provide a positive update on the club's top goalscorer ahead of Sunday's derby with Arsenal in the Premier League.
The 57-year-old added: "I believe he's going to be fit. I'm not sure, he's on treatment. But I could be now doing some bluff or trying to pretend that he's in big trouble. He's not in big trouble. I believe he's going to play."
While Tottenham have qualified for the knockout phase, only a victory at home to Royal Antwerp on Thursday will send them through in top spot and therefore ensure they avoid the sides which will drop into the competition from the Champions League.
Mourinho is confident regardless of the opponent, all of his squad will be motivated by the time the knockout phase gets under way in February after a similar scenario with Manchester United in 2016-17 when they went on to win the competition.
"When we go to Antwerp, to Ludogorets, to Linz, the stadium, the weather, the emptiness, of course at home it's the same in relation to that, but that atmosphere I have a feeling, but it's not a feeling, it's experience, that some of the players feel they shouldn't be here," the Spurs manager said.
"But the contradiction to that is players like Son and Pierre that are players starting every match, are examples of the guys that it doesn't matter where, it doesn't matter the competition, they are there and they are in front of the team every time.
"I think it's a question of attitude, which I experienced before. Even at Manchester United I had a similar situation when we lost two matches away in the group phase and when we get to the knockout (stages) you get better opponents and more difficulties, the team faces matches in a different way."
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