The catching duo just hasn't hit. In Mes' case, he may be injured, there's been talk of a hamstring problem. And maybe Mes just lost it when Hanigan starting taking a number of his at bats.
If the Reds had added a catcher who hits lefty, the XPaul spot could have been used. Xavier doesn't play much anyway.
Hanigan has hit better of late, but has no power at all. Maybe Mes will come around again to moot the issue.