Particle distributions of bursty bulk flow (BBF) events in the central plas
ma sheet regions show that the high earthward mean velocity comes from a co
mbination of energetic ion flux increases (>few keV) in the earthward direc
tion and decreases of similar energy fluxes in the tailward direction. The
energetic ion increases are observed to similar to few MeV during intense e
vents, indicating the responsible mechanisms efficiently accelerate particl
es. The BBF events are intimately tied to the dynamics of tail current shee
t reconfiguration and for the two events discussed here, they occurred 45 m
inutes and 5 minutes after the expansion onsets. The perception offered by
our analysis differs from the earlier studies which described BBF events us
ing MHD approach.