Binabik: Diskeeper will almost never do a full defrag (only 1 fragment per file) because it's just not worth it.
Defrag is usefull when your disk is so fragmented that permance suffers greatly because reading large files will imply running from one sector to another half way accross the disk. However, if when you have large chunks, there comes a point when it is more time consuming to move such large chunks around than the performance gains you may get from it. If you look at that log in detail, you'll probably find out that most of the resulting fragments are large and that few files will be spread accross more than 3 or 4 fragments (except, maybe, for really big ones)

I think this is explained in greater detail in the application's help but that's the general idea.
Still, you can request a full defragmentation somewhere in the options, if I'm not mistaken...