There are very limited number of players left that are even worth signing in the current signing period. The vast majority of legit players were many signed months ago. Dodgers clearly have their eye on a particular player, and were short on funds.
I'd rather see the Sox spend this money than not. Trading it is dumb. But its August and if the Sox had no one identified at this point, may as well turn it into 2 live arms, one of which looks pretty intriguing.