Enstrom & Shattenkirk are definitely fringe top 10 defensemen.
But so are a lot of guys.
I'm not a big fan of creating "defenseman rankings" though... because for points-only pools its basically:
etc., etc., etc.
A bunch of interchangeable guys between 40-55pts.
I honestly think there are as many as 15 defensemen that could finish 2nd in the NHL in scoring. (Chara, Campbell, Doughty, Suter, Weber, Streit, Yandle, Letang, AP, Shattenkirk, Boyle, Edler, Buff, Enstrom). And then you've got guys who could join this group if they can stay healthy like Mike Green and Andrei Markov. (both I took for this shortened season in one-year leagues).
Any of those guys listed above could finish 2nd in D scoring... or 15th.
So... sometimes doing "rankings" skew our understanding of defenseman value.