A factor here is that the switching has always put either Sordo or Paddon in good starting position on gravel events, so for the team it's actually good to run split season, as long as they have drivers that accept it. Not good for those drivers in the long term though.
For Toyota
Lappi and Latvala both got 74 teampoints. For statistics like this planetmarcus has the best table:
http://planetemarcus.com/saison-wrc/
Results:
Number of rallies Sordo retired from with technical issues: 0, number of crashes resulting in retirement 2
Number of rallies Paddon retired with technical issues: 0, number of crashes 1
Number of rallies Mikkelsen retired with technical issues: 4 (2x from 1st place, 3rd and 4th), number of crashes 1
Number of times Mikkelsen was faster than Paddon in same rally 3, faster than Sordo 0
Number of times Paddon was faster than Mikkelsen 1
If anything they should sack Paddon and give Sordo full season.