The performance in the domestic league hasn't been the best indicator anyway in the past. Sevilla was so incredibly bad in La Liga the year they won the Europa League. Back then Sevilla has beaten Manchester United 2-5 in aggregate! In the semifinal they have beaten Juventus Turin and in the final they have beaten Roma. Now if you had to guess which position they finished in La Liga, you wouldn't think they finished 12th and didn't win the last four consecutive games. At some point they were fighting against relegation. That's why I have stopped predicting based on how a team is doing in the domestic league.
Actually some domestic leagues are nothing compared to what happens in champions League or the Europa League most times an did you begin to make comparison based off the domestic league, you may be on the wrong side because a few teams do appear really good in their domestic league based on the fact that they do play there almost every season but they might not get to qualify for other leagues outside their domestic league and appearance does matter of we would want to consider experience in these league which ofcourse is an advantage, so of all of this isn't put in considering you may just have the wrong judgement about a team t a time.