Which DL3/4? Heyward, Hughes, K. Williams, or McCoy

We start two DL's and I play in a 10 team our IDP scoring includes 2 pts per tackle, 1 point per assist, 2 points per tackle for a loss, 3 points per sack, 1 point per forced fumble, 2 points per fumble recovery, 1 point per pass defensed, 6 points per interception, and 6 points per touchdown.

I currently have Ninkovich, Vernon, C. Johnson, and Heyward...but I'm thinking about dropping Heyward for Hughes, Kyle Williams, McCoy.

Would you drop Heyward for any of these guys?  Other FA DL's include Woodley, Andre Branch, Justin Smith, and Kiwanuka.

Heyward gave me nice consistency last year, but Pitt DL's don't have a history of being fantasy relevant...I'm also wondering how the recent signing and possible rotation of "the beard" Keisel will affect Heyward.

Since this is a fairly tackle heavy league, Heyward is a nice option. I really like Mccoy this year though and would go with his upside.