Jol was wrong and Comolli was right! When Comolli was DoF the players he signed increased in value so he earned the club a lot of money. That is not true of Redknapp's signings (nor Mourinho's I think).
The main source of our disagreement however is a couple of beliefs that I have which almost no-one else shares: 1) Players are more similar to each other than they look and 2) It is very difficult to tell which players are the 'best' now, never mind how they will progress over a few years.
If I asked a group of fans to put the following similar players in order of how valuable to our team they would be in 2017 I guarantee I would get almost every order possible: Livermore, Sandro, Capoue, Stambouli, Schneiderlin, Mason, Dembele, Bentaleb. Similarly Lamela, Townsend, Chadli, Willian, Lallana, Pritchard. And that is not unreasonable because no-one has enough data to know. The only way to have any chance of deciding which of those we ought to buy or sell and at what price is to have the decision in the hands of a full time person leading a team of scouts with the long-term objective of signing players who will be great in two or three years (and selling those who won't) and undistracted by the job of coaching the current squad. Getting the best four of the first bunch and the best three of the second could be the difference between being champions or being 7th.
If you don't believe this look at the records for the 100m sprint and try to work out which sprinters you would sign to have a PL winning relay team in two years time. You'd find that there is quite a scatter on individual performance which means you have to watch lots of races even to be sure which is better now and there is an even bigger scatter on when people peak and how much they improve. Now extend that to football where there are many more variables and you'll see that you probably need to watch every player for 50 matches with very detailed analysis of his performance to have any chance of differentiating.