I think Simpkin has some up side still ,but Talin is nearly the finished product ,and Croker who was never a proper 9 in any case ,cannot be left in that position i don't think.
For me Croker maybe has potential to be a good 13 (good D should have enough passing as an X 7 and enough speed,certainly quick er that Jake) ,but he is not a serviceable 9 .A fact thats been proven by Simpkin even though he is not top shelf .
As other s have said we have a few coming up from the young guys and TBH from what I have seen of Simpkin I think we should spend the cash on a top line FR that Simpkin can run onto the ball at pace unlike what Croker has shown to be capable of .