You are right, besides Liverpool doesn't often lose to bigger team like that. The smaller teams puts you to an edge, they try as much as possible to frustrate your efforts and in some cases they end up winning at the end of the match unlike when two big teams meets, they are fighting to be the one on top. I think the match is even for both teams. They both have big names with quality that will go head on with each other, this is where people normally say anything can happen. In these kind of games, there's no favourites because any of them.can win, sometimes they will play draw. These big teams play out their hearts when they meet another big team..
The mentality of the players is not the same when playing against big teams and against small teams. Liverpool has a tendency to lose against small teams, this is completely due to mentality and underestimation. Since there is no opportunity to underestimate big teams, their mentality is strong and they try their best to win the match. Against small teams, basically strong mentality and effort are not used 100%, which is why we often see big teams losing against small teams. The mentality of small teams also plays a role in unexpected results in these matches.
Liverpool is strong with the best squad in exciting matches, but whenever they have to put their bench squad on the field, that is when the main danger arises. Last season, their young players failed to perform well, which is why we saw some unexpected defeats. This performance has continued this season.