a 5* QB and a 2* WR? Okay.
a 4* K and a 1* QB? No thanks.
The line is somewhere in the middle. Having one bad WR won't kill you, because you have 8-12 on the team at a time. Having one bad QB could kill you because you have 3-4 and you might need all of them. So, in order from most willing to take to least willing:
WR/TE
OL
DB
DL
LB
RB
K (mostly because I don't want an extra one on scholarship who can't kick)
P (ditto)
QB
The importance of the star player also factors in. Is it the WAR for the star player noticeable? If it's a 5* QB and I just have 2 2* QBs, then I'm more likely to take him. If it's a 5* safety and I have 2 4* safeties already, then i'm less willing.