There are another few points I would like to add.
Point 1. A team that wants to be successful/good/great has to have that fine balance between attack, midfield and defence. If you have great strikers and score loads of goals but leak too many at the back, chances are the team will not win too many games. No point scoring 2 or 3 and conceding 4 or 5. A loss is still a loss and means 0 points in a league situation or elimination from a knockout style competition.
A team with a very good defence but no teeth at all in attack might fare a bit better but not really achieve much too. Drawing 0-0 gives you 1 point but means no progress in a knockout competition, and playing for penalties will not always work out. It is highly improbable that any team will always win from spot kicks. Lady Luck will not likely to be with one all the time. 1 point is better than 0 points but still less than a 3 point win.
Thats why the ideal situation would be to have a team with a good balance between defence, midfield and attack. The Liverpool teams of the 1970s and 1980s and Man U teams of the 1990s and present Chelski team have that fine balance, therefore their respective successes are self explanatory.
The main weakness and the Achilles Heel of the 1990s Liverpool team was
1. Not having adequate defensive cover.
After Alan Hansen retired from playing in 1991 Liverpool lacked that solid and commanding central defender and the secure and dependable central defensive partnership which had been the foundation of the successful Liverpool teams of the 1960s to the 1990s.
From the giant Ron Yeats of the 1960s to the magnificent partnership of Alan Hansen and Mark Lawrenson in the 1980s (still considered by many to be the best central defensive partnership in Liverpool's history and even the modern history of English football), Liverpool had a good defence at the back which gave the team confidence and protected the goalkeeper.
The saying "The foundation of a good team starts from its defence" is almost definitely a correct and true statement and there is almost no doubt a very appropriate one. There are so many examples of good/great teams having that solid central defensive partnership. Some I can think of are
Desailly/Blanc France in the late 1990s till 2000.
Ayala/Samuel Current Argentina team
Bruce/Pallister (early to mid 1990s Man U team)
Thats where Liverpools failings were in the 1990s. One of the major weaknesses and inadequacies of Liverpool under Roy Evans was conceding soft goals and goals from the air and from set pieces like corners and free kicks near the penalty box and goal.
It was only after the arrival of Sami Hyppia and Stephane Henchoz that the cracks were sealed and holes were plugged. There was again that dependable central defensive partnership and at present Hyppia/Carragher are doing a good job. (Thank Goodnesss!)
2. Not having that hard tackling midfielder General/ball winner and leader in the centre of the park.
The great Liverpool teams from the 1960s till the 1980s always had that 'tough guy' hard tackling/ball winning midfield general and commander in the centre of the park from the indomitable Tommy Smith in the 1960s to 1970s to Graeme Souness in the late 1970s and 1980s, when Souness left for Sampdoria in 1984 there was a gap which was plugged upon Steve McMahon 's arrival in 1985. Steve McMahon was the last of the great midfield generals until Steven Gerrard came around in the present.
The absence of this midfield general was another weakness/failing of the Liverpool teams of the 1990s. Players like Jamie Redknapp and Paul Stewart were just not up to standard. They are not the Roy Keane type who can boss the midfield. This was another area that Liverpool were weak in until Stevie G came along and this is another reason why Liverpool are performing better at present.
3. Not having a steady and dependable goalkeeper.
Lets not kid ourselves, of either David James or Peter Schmeichel, who would one rather have? (Assuming Peter Schmeichel is still at his peak). A steady keeper is vital to the team too and a great one can organise and keep his back four on their toes and inspire confidence in his team.
After the brilliant Ray Clemence in the 1970s and the good Grobbelar in the 1980s and early part of the 1990s, Liverpool did not have a reliable keeper after that during the Souness and Roy Evans years. David James was so error prone and the weak defence hardly helped his confidence either.
It was only after Sander Westerveld came along that stability in the gaolkeeping department was restored and at present Jose Reina seems good between the sticks and explains Liverpool's good defensive performances. Thank Goodness again that this issue has been sorted out!
Scott Carson can get better with age and experience and more practice and seems to be a bright one for the future with loads of potential. Chris Kirkland is undeniably a great one for the future too but there has been some indications he wants a permanent move out of Anfield.
These were the 3 main weaknesses of Liverpool that explained their inability to do well in the 1990s. Of course there were other weaknesses as well but those 3 I mentioned were the main ones. Feel free to add on to my comments/ statements.
Rafael Benitez has thankfully plugged those gaps and rectified (to a certain extent) those main weaknesses but there is still work to be done and areas of the team to be strengthened. Hopefully Rafa will manage to do that. After all there is always room for improvement and it is only through constant improvement that can lead to success and lead on to further heights.
The Best Is Yet To Be!!!