The FO obviously thinks the bigger changes will be coming later - either at the trade deadline, or after the buyout period. That's why we've done nothing, and now are just looking at 10 day contracts.
On a 10 day contract (with a low probability that we resign a player afterwards) I'd rather have Derrick Williams than Farmar -- we know what Farmar is...
I'd rather have Stephenson, I agree -- maybe the Cavs thought the attitude issues were too big for a guy who would likely be gone in 10 days anyway?