From what i remember Tacchinardi wasn't particularly great at passing or going forward, but he knew his limits and it worked well because it allowed Davids to push forward and link up more with the likes of Zidane as well as the wingers or full backs.
Yes i agree tacchinardi was a better passer than sissoko but i think sissoko is a better destroyer overall.
Makelele knew his limits and played to them, Gattuso also knew his limits, did the hard work and gave it off to the likes of a pirlo or seedorf.
The teams these players played in, that being tacchinardi, gattuso, makelele all had lots of movement and were in a system that obviously worked well and the teams were the best in their era.
If we sell sissoko, we'll still need to bring in a player who is going to make the hard tackles and do the hard work. Melo and Marchisio are not these players and I dont think Poulsen is at the level we should be aiming for.