Just a guess but I'd say:-
- Connection is likely prioritised and the fact they are publishing ping figures rather than just bars or outright hiding such elements knowing they can be caught suggests this may be the case. They have falsified this shit in the past where it was totally removed or masked in later COD titles.
- 'Skill' is probably more attributed to form, possibly in 5 game blocks of averages rather than outright k/d.
- Clans are being matched against other clans when possible so a low skilled/reverse boosted party leader can't take a team of pub stompers into a low skill lobby. If no other team is available, they are probably being put into high-end form lobbies or ones comparable to the party leaders form.
I do think once connection quality is established, then skill becomes a factor for matchmaking so it's possible both of these elements are working hand in hand and are equally important.