note that index defrag and index rebuild are very very different, the table was badly fragmented, I can't understand why you need to rebuild the table with 80% fill factor btw, you can't recommend a fill factor unless analysis of the table has been done to establish the optimal setting - first thing I always do is remove fill factors unless there is a justified proof for it, all you do is bloat database size, increase scans and readahead and increase io.