I think analytics goes well beyond following, although that surely is a data point. If they used analytics from my twitter feed the would surely know that by far the poultry 1,500 followers I have, are mostly fellow Chelsea fans. They would know that most of the football media that I follow is centered around Chelsea. They would know that most of the transfer tweets I click on are Chelsea related. They would know that most of the player's tweets I click on are Chelsea related. I imagine that the analytics behind marketing to person is enough to determine what team they are most aligned with.
I'm sorry, but I have no idea what you're trying to convey with most of your post. Do you want a gold star for being a Chelsea Twitter ultra? Unfortunately there is no information attached to the "analysis" you posted, but to me it looks like they just took the number of social media followers of each club and then added another "total bar" that just summed all of them up to double the count. The latest FML lists Chelsea at 110mil social media followers and what do you know? That corresponds perfectly to your diagram.. United are listed with 176,8 million followers on FML and what you do you know? It looks like a perfect match. Liverpool at 105 million followers.
It seems like this careful analysis 100% mirrors the follower numbers, what a shocking coincidence.