The Reds raced into a 3-0 first-half lead thanks to a Roberto Firmino brace, either side of a Sadio Mane strike.
But Liverpool’s questionable back-line suffered a horrendous collapse which shell-shocked Jurgen Klopp’s side.
The Reds know all about recovering from a 3-0 deficit in the Champions League as they did just that to win the 2005 final against AC Milan.
But they were given a taste of their own medicine by the La Liga outfit who secured a vital point which takes their qualification hopes down to the final group match.
“I think every goal there could have been prevented,” Ferdinand told BT Sport.
“The penalty from (Alberto) Moreno, the free-kick from Moreno and (Ragnar) Klavan’s header, he could have headed it out in a different direction – he headed it down into the box where the bodies where.
“I just feel this Liverpool team at the moment don’t know how to defend.
“They weren’t playing the way they were in the first half.
“You have got to be able to sit back and say let’s soak up the pressure and defend as a team. They weren’t able to do that.”
However, Ferdinand does think Liverpool should take the positives from their attacking performance.
“This is a crucial time now,” Ferdinand added.
“The couple of days before the weekend is down to the management to really galvanise the team and lift the squad up.
“They have to try and take some positives from this, in terms of their attacking football.
“They’re better when they play on the front-foot but the best sides can mix and match.”