  The role of the delta isobar degrees of freedom in nucleon-nucleon scattering
is revisited. We attempt to understand why the dimensionally regularized
two-pion exchanges with the explicit delta isobar is much stronger than the
ones with spectral function regularization. When the cutoff value of spectral
function regularization is varied, the isoscalar central component exhibits a
rather large cutoff variation. This reveals a surprisingly large numerical
factor of the deltaful two-pion exchange potentials. The power counting is
adjusted accordingly and we discuss the results and how to improve upon this
finding.
