Possibly need to look at their grade control processes to get the predicted grades . As you say - predicted vs actual grade seems to be the obvious problem child but there can be numerous reasons for this and you need expert advice and good people to work out which things are causing the problems and which ones are the quickest easiest "wins". At least they are in the sulphides now so that may help recoveries.
Seems to be more ore volume but at a lower grade than expected so they need to adjust their plans to be able to correct any further problems before they mine themselves out of business. No point having the experts identify what the problem is if you are taking the last cut from the bottom of the pit - too late then.
Another possibility is that there is something wrong with the expected grades (i.e. the resource model predicting high grades that just aren't there and maybe the grade control estimation exaggerating the predicted gold grades) so they need to rule these in or out before throwing more reagents at the problem.
The other thing that is apparent from this news release is that there are problems in the mill as well, so before we go crucifying the geological and grade control people they had better also look at why the cyanide consumption is so high. The first place I would be looking is the older Minproc and Placer Dome metallurgy reports from the Chinova Osborne site records because thats where the gold circuit was first commissioned when Placer Dome built it before they ceased using it, switched it off and just installed gravity knelson gold concentrators (not a big deal at the time as most of the revenue from Osborne came from the copper sulphide and the knelsons were able to recover decent amounts of gold), if I remember it correctly the gold circuit had a very high cyanide consumption and might be worth looking as to why it still does this, even though its been essentially unused then dis-assembled and reassembled at Lorena and is seeing very different ore than it first saw but is still consuming cyanide.
Outside consultants needed I think - both on the geological/grade control side and possibly the milling and gold recovery plant end as well.
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