Must win game, who to get?

[FonFatty]

This week I have a couple of must win games in my leagues and as a result I have to trade out my old buddy Michael Hibberd if he is not named this week. Whoever comes in will be my D7, and these are currently the lads I'm looking at:

Dyson Heppell - This guy is almost the perfect D7. Not injury prone, won't be rested. And going by his current form should score at least 85 each week.

Jack Grimes - Seems to be the shining light in a rather dull Melbourne team at the moment. Has potential to score big, won't be rested either, but his injury history turns me off quite a bit.

Sam Fisher - Is dirt cheap at the moment for someone of his potential. Can put up some massive scores, but is his fantasy career all but done now that Dawson is gone and he has to play as a lockdown defender?
I'm also considering Yarran, Newman and Rance, but feel as though the above guys would be a better fit.

For the record my backline is currently: Deledio, Goddard, Scotland, Waters, Suckling, Lake, D7 (Shaw, Darley)

Would appreciate any comments, thanks!

Looking at the their run home there are only 2 games I can see where Fisher wil be used as a lock down defender, that is the rnd 19 game against the pies and the rnd 21 games against the cats (2nd week finals), now he might be freed up against the other teams where he has the chance to score heavily. A nice cheap POD player IMO. He could finish the season with a bang.