set j_f_name /path/to/transition/report/max_transition.rpt
set j_f [open $j_f_name r ]
while { [gets $j_f line ] != -1 } {
    set j_load [lindex [regsub -all " +" $line " " ] 0 ]
    set j_driver [get_object_name [get_flat_pins -of [get_nets -of $j_load ] -filter "direction == out" ] ]
    puts $j_driver
}