You can try with something like:
find /usr2/devel_snapshots \
-type d \
-maxdepth 1 \
-mindepth 1 |
sort -r |
head -5 |
xargs tar -X $BASE/synclive_exclude.list -cf - \
/usr2/docs /usr2/devel_backup /usr2/devel_config \
/usr2/devel_logs /usr2/devel_reports /usr2/doc-files |
gzip > $DUMP_DIR/stage/usr2.tar.gz &
ls, sort and head will get the latest 5 directories and with xargs you can give the results as parameter to the tar command