Properties of the nucleon exchange and the direct nucleon pole terms are studied in the diffraction dissociation JrN~>r. (N7r). It is shown that contrary to the naive expectation, the nucleon exchange term with the s-channel helicity conserving 7rN scattering amplitude cannot give the maximum at ¢aJ=O in the ¢aJ distribution. The transverse momentum distributions in the lab. frame reflect well the cos eaJ but not the ¢aJ distributions. We need something besides the pion exchange term to enhance the backward side, cos !JaJ<O, bnt it is questionable whether the nucleon exchange term plays the role of something completely. Including cross-over phenomena, it is qualitatively examined that the resonance production term plays the role of the something.