Usually it is more difficult to play with 10 players than with 11, this is when a team with a numerical advantage needs to score

Usually yes but as you maybe have seen in the case of Westham they have played very well and good with only 10 players.
And yeah you are right that Frankfurt should be score the second goal in a few missed chances they got .
Anyway i am glad and happy that Frankfurt managed to get in the final , as they deserved it and i hope they will win the Europa League.
It seems that when facing Frankfurt, having to admit that losing one player in the 19th minute made it even more difficult for West Ham to
face Frankfurt. West Ham's error made it easier for Frankfurt to dominate the match, and can finally win the game and make sure they qualify
for the final. Besides, I saw that West Ham had really struggled against Frankfurt since the first leg, because after all Frankfurt in the Europa
League competition was very on fire, especially after they managed to get rid of Barcelona. It's very different from Frankfurt's performance
in the Bundesliga, so I agree with you Frankfurt really deserve to qualify for the final.
Next in the final Frankfurt will face Rangers, it was a shocking final for me, because I didn't expect these two teams to make it to the final.
I predict Frankfurt will win the Europa League, after they managed to get rid of several strong teams, they should be able to beat the Rangers.
But Frankfurt must be wary, because Rangers can reach the final not by chance, it proves Rangers is a strong team too.