FH is just one of the two rallying shots in tennis, yeah
. Taking into account other factors. Del Po has the superior power.
Dont forget the serve aswell.
If you cant generate pace on return, your opponent will get in command and rally mostly to your backhand.
On your serve your opponent might just slice returns to your backhand like Federer does alot to Delpo (and not to Berdych).
Tsonga, Delpo got similar weak backhands and weak returns that make their game look less powerful. Against Berdych at full flight there is no where to go.