The English teams are playing under a burden of pressure. Man Utd and Spurs falling in the semis to weaker opposition would make the PL look weak. Ange and Ruben must get their teams to win.
The Europa League semi-finals this season have not started because Manchester United and Tottenham Hotspur are still in the semi-finals to make a better victory. You don't need to doubt the teams from the Premier League because they are only under pressure when playing in the Premier League, but in the Europa League both are still equally strong and have advanced to the semi-finals in such good condition.
Europa League isn't as tough as the Premier League and that's why you see that United and Tottenham are finding it difficult to cope in EPL because there are too many clubs getting stronger everyday. However, in UEL the competition isn't that tough and fierce compared to EPL which makes me believe that, we would see one of the EPL teams in the finals.