I took a look at Mikkelsen´s performances this year:

Monte: alternator problem early in the rally, after restart some good times (fastest guy on day 3)
Sweden: good and solid job, ended on the podium
Mexico: okay rally from him, became fourth, behind Sordo tough
Corsica: really disappointing performance, “didn´t have the feeling”
Argentina: was leading after the fourth stage, puncture in SS6, finished in fifth place in the end
Portugal: power steering problem on day 2, but no good stage times at all
Sardinia: leading after the fifth stage, gearbox issue made it impossible to set any good times afterwards
Finland: a real disappointment, slow times, off road on SS4
Germany: another disappointing performance, solid sixth place, but mostly due to the mistakes of other drivers
Turkey: battling for victory, ended 5th due to driveshaft issues
Wales: feeling was missing again, disappointing sixth place

So obviously the pace was missing in Portugal, Finland, Wales and at the tarmac rallies (as it has been already said before). Lot of bad luck as well, he definitely deserves another chance next year. I don´t see any reason to drop him.