how to explain this table status

[rei]

I have a database with large datas in it.
A lot of unused INDEX were created, and it decrease the UPDATE performance.
Thus, i decided to drop all the unused index.

[ table status of OLD(a lot of unsed index)]
Name: old_table
Type: InnoDB
Row_format: Dynamic
Rows: 6274133
Avg_row_length: 479
Data_length: 3009413120
Max_data_length: NULL
Index_length: 1324630016
Data_free: 0
Auto_increment: NULL
Create_time: NULL
Update_time: NULL
Check_time: NULL
Create_options:
Comment: InnoDB free: 88702976 kB

[table status of NEW(with all unused index dropped) table]
Name: new_tb
Type: InnoDB
Row_format: Dynamic
Rows: 5694990
Avg_row_length: 528
Data_length: 3010461696
Max_data_length: NULL
Index_length: 449544192
Data_free: 0
Auto_increment: NULL
Create_time: NULL
Update_time: NULL
Check_time: NULL
Create_options:
Comment: InnoDB free: 88702976 kB


although the new_tb has fewer datas, the Data_length is however bigger..
can i consider whether the structure is bad?
but Index_length decrease and does this give update statement better performance?