You can play as good as you want, if you dont win the decisive battles, the decisive challenges, you have no chance in football, Klopp told TNT Sports after Thursdays 3-2 loss.
The manager later added: We were not aggressive enough. They won all the decisive battles, challenges, stuff like this.
We gave balls away easily: first goal, Im not sure the second goal, third goal last line too deep. So real mistakes.
It was evident from the start that Toulouse, roared on by their biggest crowd in over a year, were more up for it than their Europa League visitors.
But Klopps assessment particularly rings true of his midfield, comprised of Wataru Endo, Harvey Elliott and Alexis Mac Allister.
* Statistics via FotMob
While Elliott was among the standouts on a tough night, Endo and Mac Allisters statistics from the defeat highlighted Liverpools lack of aggression.
Per FotMob, only Luis Diaz (10) lost more of his duels than Mac Allister (nine) across both sides, with the Argentine winning just two for a success rate of 18.2 percent.
Endo, who came in as defensive midfielder ahead of a possible start against Brentford on Sunday, won two of his eight duels, or 25 percent.
The Japan captain failed to win any of his five ground duels, while only Toulouse right-back Mikkel Desler (five) committed more fouls than Endos four.
Neither Endo or Mac Allister won a tackle on the night.
Another player who struggled to show any intensity was Cody Gakpo, who won only two of his 11 duels on the night or 18.2 percent.
Elliott was one of only four players to start for Liverpool on Thursday who won more duels than he lost, the youngster successful in five of his seven (71.4%).
The inability of Endo, Mac Allister and Gakpo, in particular, to win challenges and regain possession played a significant part in the failure to secure a result which would have guaranteed a spot in the last 16.
Overall, Liverpool won only 37 percent of the evenings ground duels, with Toulouse dominating with 63 percent.
Klopp was right to point out a lack of aggression, and the hope is that his frustration after the game will translate to a fighting performance at Anfield on Sunday.