Yes indeed, Rayo Vallecano is not a completely weak team, and although Rayo Vallecano lost to Barcelona but Rayo Vallecano is also still in the top six of the La Liga standings this time. In addition, based on head to head records, the fact is that Rayo Vallecano rarely lose with a big score against Barcelona. So yes, the victory with a score of 1-0 is still a good result for Barcelona, because only with a narrow victory it is enough for Barcelona to still be able to stay at the top of the standings. I also only bet Barcelona -1.5, in fact still lost, but I still accepted the results.
Barcelona as the better side has got the victory and they has a superior and better performance getting them to be deserving of the Victory they have won so far. But then a one goal margin felt literally like a weak victory which we had expected even more from them seeing the difference in the kind of victories they have gotten recently especially against teams that are within that very average form and strength.