Lob data type and chained rows detected and SYS table migrated rows removing method

Hello,

I have two questions:

1. I have a big user table with a BLOB column.This table is 17G but when I use analyze table compute statistics and query DBA_TABLES ,it only show the average row length is only 321 bytes. why no chained rows detected in this table?

2. I have some migrated rows in SYS table,can I use regular "alter table move "  to reorgnize those SYS table? Can I also change PCTFREE parameter for those SYS table?

My Oracle is 10.2.0.4 EE and OS is Windows Server 2008.

OWNER                     TABLE_NAME                     PCT_CHAINED  CHAIN_CNT AVG_ROW_LEN   NUM_ROWS   PCT_FREE   PCT_USED