That has norhing to do with it.
stat site parse top 200 players match info. So unless there is less than 200 UKF players in rank, standalone DLC cannot be the execuse for the low match count.
It's slightly different to what it implies. Site creator explained it. While it takes data from top200 players, it also accounts for games played in modes on which those players are not top200.
If someone is ranked top100 in 4v4 random and top1500 in 1v1, his games in 1v1 will be accounted for as well.
The fact that a faction is also less played (you can check the amount of ranked players in coh2 official leaderboard means that you can make 1:1 comparisons between ranks. Someone ranked 200 UKF is way worse than someone ranked 300 as Soviets.
You can view entire march stat if you want(but only supports weekly/daily view at the moment).
And result is worse if you do. haha...
Underpicked & low win ratio means something. If win ratio of 23% doesn't mean something, what does?
And I have to mention that this ML was played im pre-winter patch version. And AFAIK, UKF got nerfed in winter patch. So... good luck to UKF for next ML & 2021.
UKF is in a rough spot, but i'm explaining WHY some of the factors you include can't be translated directly as it been a clear issue.
Each pro player has a distinct playstyle and preference. Even when UKF was broken, some of them just played USF/SU. UKF will always be underpicked unless obnoxious OP at which point it barelys breaks even with been the 2nd most picked faction or on pair with the most picked one.
1v1
320/699
260/620
262/549
309/655
That's 45.62% That's low but fairly in the range of statistically acceptable accounting for the factors i mentioned before.
If you talk about the 4v4 margins, yep, that's more of a clear issue.