Why does the value of Δo increase with increased charge on the metal?

A greater positive charge means the ligand is strongly attracted and pulled closer, and thus it creates a stronger crystal field. The potential energy value of the barycentre should thus be higher, since repulsion experienced by the d electrons is stronger. Why is though the value of the Δo increased - the potential energy difference between the various differently oriented d orbitals? Each orbital experiences stronger repulsion if charge on metal ion increases and the ligand is pulled closer, but how can anything be said of the energy difference Δo? Both *t2g* and *eg* are at a higher level, that's all. 


