Oh, and because P6 is a Spanish airline, perhaps it was decided that MAD was a good candidate for replacement; for logistical reasons there's less repositioning needed. Their HQ is on Mallorca but it seems they have a base in Madrid already; I guess the Madrid route was a total no-brainer then for them to take from KLM.

But that's not to say that P6 are only replacing KL on (some) Spanish routes; these wet lease operators will typically operate anywhere in the world, as required.