Well assuming you only start 3 and they can of any position, I tend to like your guys just fine. Barring injury or excessive under-production, I would probably just go ahead and keep them. I would however, be keeping my eyes on Jackson, Davis, Conner and Hawthorne.
In tackle leagues where things are NOT weighted towards big plays, consistent tackle machines like the three you've got are perfect. You really don't need anything other than linebackers, which is what you have. Safety's are next best. I wouldn't even bother with linemen or CB's.....