Jamie Vardy scored twice for the rout.
Siewert said, “First of all I have to say the credit from our side to Leicester as they were much more clinical than we were.
“We tried everything, and this is exactly the quality in the Premier League I would say.
“In the situation where they have a 50/50 chance, they score, we need too many possibilities to score then."
Steve Mounié had an excellent chance to grab a goal after coming on as a second half substitute and Siewert acknowledged that the striker tried everything in order to change the game.
“Steve came on the pitch and tried everything.
“He had his chances, so he showed that he wanted to change the game, unfortunately he could not, but he tried everything to do it.
“When we had the momentum it's like a mirror of the season and then the opponent has the momentum to score, and they do it."