|if they want to optimise their chances of going back to back in October.|
No matter what happens this week, Collingwood's premiership chances will most likely be decided on the last weekend in September when they will have to face one of Geelong, Hawthorn, St. Kilda or Sydney (GHSS) in a sudden death "preliminary final" (that in any other sport would be called a semi). Yes, they will know by Saturday arvo which of Geelong and Hawthorn have already booked their place in a prelim. If it is Hawthorn that would make this case overwhelming, so lets look at the rest of the story.
Player management aside, and there is a serious issue with players in their second game back after a long break, if boils down to the neat symmetry of the current finals system not having the highest likelihood of producing a 1v2 (grand) final.
If Collingwood lets West Coast win this week, West Coast go straight to a home prelim which gives whichever of GHSS is left in that half an always challenging road trip the week before the final, where they either lose getting 4th placed West Coast through to the final or win and have the extra recovery load. Meanwhile Collingwood stoke AFL coffers (the main reason for their continued existence) against Carlton or Essendon and get back to their full strength for the prelim that will (as so often in recent seasons) be the real decider. Taking that route to the final, it might not have even needed to be October.
By winning against West Coast, a still underdone Collingwood would face the almost certainty of consecutive games against two of GHSS, given that West Coast would be unlikely to win an MCG prelim against any of GHS. (If Sydney unexpectedly conquers two of GHS and West Coast, having lost in week one, expectedly wins a home semi(quarter) against Carlton or Essendon, which of them gets the home prelim? This doesn't really matter to Collingwood's choices this week.)
While the underlying math is beyond the scope of this post, the dilemma Collingwood faces this week only underlines the at first sight unlikely structure of a fairer final series in which the "qualifying" finals become 1v3 and 2v4, but everything else stays the same. When such a structure goes with form you finish up with the true semi (prelim) round being 1v4 and 2v3 which is as it should be, not the way it is now where that is impossible. (The math works out to give everybody a genuine incentive to finish higher, rather than the situation now where 4th is more likely to get you into a grand final than 3rd who probably have to beat 1st to get there.)