There has been mention of a role in defense of football called "Sweeper". [Wikipedia](http://en.wikipedia.org/wiki/Defender_%28association_football%29#Sweeper_.28Libero.29) gives the following explanation.

> 
> The sweeper or libero (Italian: free) is a more versatile type of Centre back that, as the name suggests, "sweeps up" the ball if the opponent manages to breach the defensive line. Their position is rather more fluid than other defenders who mark their designated opponents. The sweeper's ability to read the game is even more vital than for a Centre-back. The [**catenaccio**](http://en.wikipedia.org/wiki/Catenaccio) system of play, used in Italian football in the 1960s, notably employed a defensive libero.
> 
> 
> 

My question relates to the diagram of field positions shown below. If the sweeper is played, there will be 5 in defense. But from reading the wiki page, it seems that the sweeper's role is to read the game so that he wins the ball by tackling the opposition attackers, and also to make the forward run to start the counter attack.

**In that case isn't the role of the *sweeper* same as the defensive midfielder (DM) now, except that DM will be in front of the defenders?** 

Can we say now since the sweeper's responsibility is shared now by both the defensive midfielders and the Centre backs, the sweeper's position has become obsolete?

[![football field with showing defender positions](https://i.stack.imgur.com/PYGgUl.png)](https://i.stack.imgur.com/PYGgU.png)  

*(click for full-size image)*