I agree that a tall anchorman can be a reliable aerial presence. I have Carvalho on an Arsenal save and when crosses come in it is like having three center backs. The proactive instructions of a DMd mean they are less reliable in performing this task, they are too likely to be dragged out into closing down the cross.
The other benefit of an anchorman is that they allow you to ask players in the central midfield strata to 'close down more' without the team vacating that vital space in between midfield and defense. If I want the team to play a more pro-active pressing game I thus end up counter-intuitively picking the more static role in the dm strata to mitigate against the negative effects of pressing.