The Kop were heavily linked with Southampton's Virgil van Dijk over the summer.
The centre-back handed in a transfer request to try and force a move to Anfield.
But he stayed at St Mary's and many have questioned Klopp's decision not to push harder for the Dutchman.
Liverpool were held to a 2-2 draw against Sevilla at Anfield tonight and fingers were pointed at the defence.
And Klopp says one man cannot solve their defensive problems.
He explained: “I know here a lot of people were looking for this, at the defence, that we didn't sign this and that and all that stuff.
“If these problems would have been sorted with one player, you can imagine we'd put all our money in and say 'let's do this'. It's not about this.
“It's of course concentration, it's nothing else in this situation.
“We started the game good, kind of dominant, played football, had immediately good moments and they score from pretty much their first offensive situation.
“That's a mixture of being unlucky and being a little bit 'through the wind' as we say in Germany.
“We need to learn to be dominant and not to give easy goals away.
“The first one was for sure unnecessary and too easy, and the second I've absolutely no clue how they came through so I have to see that again.
“It's not a general defending problem but we need to improve 100%.”
