Truth is, the only two who are abysmal and never play well are Smith and Perch.
There is no reason to keep them, and they MUST leave.
Xisco, Lovenkrands and Campbell I wouldn't shed a tear over, and I like Lovenkrands as a person a great deal. Always seemed a top bloke.
Guthrie, Williamson and Ranger have more to give, esp. Williamson. Keep.