Halo MCC Wrong Stats and Highest Skill reported

Hello everyone, I don’t know why but my multiplayer stats and highest skill are different on MCC from Waypoint.
For example, on Waypoint I have 776 multiplayer games played, 446 victories and 9009 kills, while on MCC I have 511 multiplayer games played, 388 victories and 8891 kills.
My highest skill is 12 for the Halo 4 playlist but on Waypoint is 9; why?
I don’t know if it’s just my problem or other people have noticed this, however I thought to report this issue.