I haven't sold a single domain name with either and yet I watch crazy names sell all the time that just make no sense at all.
It's mostly due to luck and the law of averages.
The often not so great names which are in DNJ for high prices sell because it is often an end-user who wanted the name badly (for whatever reason) and made a substantial offer, far more than what domainers would value it at (and no doubt never even asked about traffic stats).
Let us assume (I don't recall the actual numbers) say 1% of the domains sell each year (high priced ones often to end-users). If there are say 10 million for sale it means you will see 100,000 sales with a number of them reflected in DNJ based in the law of averages.
Let us also assume you have a portfolio of say 1,000 names. Assuming 1% on average sell per year it means your sales would be 10 domains, and 990 did not sell, which makes you wonder how sales could be so bad!
Marketing of your domains will rarely if ever better the averages except maybe help domainers flipping on forums or mostly low-end sales to other domainers.