find drp/ -depth -name "*abc.tab" -exec rename 's/abc.tab$/xyz.tab/' {} +

rename 's/^[*]+/sprintf("%d_", length $&)/e' -vn *

$ touch *{,*{,*}}abc.tab
$ rename 's/^[*]+/sprintf("%d_", length $&)/e' -vn *
***abc.tab renamed as 3_abc.tab
**abc.tab renamed as 2_abc.tab
*abc.tab renamed as 1_abc.tab

$ rename 's/^[*]+/sprintf("%d_", length $&)/e; s/abc/xyz/' -vn *
***abc.tab renamed as 3_xyz.tab
**abc.tab renamed as 2_xyz.tab
*abc.tab renamed as 1_xyz.tab

python3 path/to/rename.py </path/to/files>

****banana.txt
**monkey.mp3
**************test

4_banana.txt
2_monkey.mp3
14_test