Now, the stats are what they are, so how do we assess who were the absolutely worst 5 defenders?
Well, Dan Issel and George Gervin, if you include their ABA stats, don't even make the list. So they get a pass - terrible defenders admittedly, but were better as younger players in the ABA. That leaves 15.
Ricky Pierce and Mark Price are similarly awful, but they had fewer minutes than most and less time to rack up defensive Win Shares. 13 left.
Then I'd say if you are in the "best" 5 of any defensive category that I will give you a pass -- so Mitch Richmond, Dale Ellis and Rudy T. get out on one category and Lou Hudson, Dick Van Arsdale and Rolando Blackmon get excused for being top 5 in another. That leaves the worst 7 guys.
Worst 7 Guys:
Kiki Vandeweghe, Steve Nash, World B. Free, Stephon Marbury, Calvin Murphy, Deron Williams, Tiny Archibald.
All guys are historically horrible defensively for people who have racked up at least 50 offensive win shares. (Only 126 players in the history of the game have had 50+ OWS).
If you sort the stats, it is pretty clear that there are two categories of terrible defenders here:
Super Super Horrible --
7. Nate Archibald
6. Deron Williams
5. Calvin Murphy
The 4 Worst
4. Stephon Marbury
3. World B. Free
2. Steve Nash
1. Kiki Vandeweghe
This final group includes the 4 worst guys in both defensive categories. Vandeweghe accounted for a Defensive Win Share around every 2800 minutes of play. Marbury about every 2300 minutes, Free about every 2000 minutes. It could be argued that Nash's ability to stay on the court for almost 40,000 career minutes makes him the worst defender of all time, since he was so bad (one DWS every 2,350 minutes or so) over such an extended period of time. But Vandeweghe's ability to toil for 24,000 minutes while NOT ACCOUNTING FOR DOUBLE DIGIT DEFENSIVE WIN SHARES just stands all by itself as an achievement.
I mean, look, all of these guys are terrible defensively, but most of them are getting one DWS for every 2-5 OWS's Nash and Vandeweghe were getting SEVEN OWS by the time they got one DWS.
They stand head and shoulders above everyone as one-end offense-only players. And much as it is hard to imagine, Steve Nash was a slightly better defender than someone else.
(It should be noted that for guys with under 50 OWS, Michael Redd and Nick Van Exel are bottom of the barrel defenders).