Which were the races that Dimension Data have animated? They've got plenty of wins from sprints, but that doesn't count as animating the race in my book. Cummings has got a few wins WT from breakaways and that's it. If anyone, it were Cannondale who were using team-work to animate some stages during the Romandie, Giro etc they were also very active in San Sebastian and Plouay. Maybe there were races in which DDD did the same, but I don't recall out of my head, so I ask for examples.
Being WT-worthy team is also about depth and Cannondale beats some other WT teams hands down in that aspect. Even during the season in which everybody complains how poor they are, they were outnumbering pretty much every other team in the mountains in 2 out of 3 GTs and they'll end up with the amount of WT points that allows them to put safely a couple of other teams behind. As far as I can see, there is even a chance they'll be top10 in teams ranking with Vuelta points counted if they don't lose a lot of points to the wrong teams in Montreal. And the points system is not doing them any favours, because if it counted points from all riders instead ot the best 5, they would've gained more than most. Mind you, being WT is not about shining in few important races during the year, as you can do it as a pro-conti team, but about being able to line-up a decent team for every race in the calendar. I think there are a lot of races in which teams like FDJ or Lotto-Jumbo have largely inferior line-ups compared to teams like Cannondale. I think there are better candidates for relegation if you insist Dimension Data should be kept as WT.
Keep in mind that Cannondale are keeping all of their best riders for 2017 and are bringing in Vanmarcke. Also some riders seem to be back on the track recently, so there is very good chance that the next year will be better than the current one for them, if the current one is not enough to warrant them a WT status. The lack of WT wins is circumstancial to some extent (they were so close a couple of times: Quebec, Plouay, stage 18 during the Giro) and should not be used as the main argument against the WT status for Cannondale and other arguments also don't seem convincing for me.
One big loss for Cannondale for 2017 will be Moser. He has not achieved many results for himself, but his versatility makes him awesome GT domestique. I want to appreciate his dedication and hard work for his team-mates during this Vuelta even though he knows he will be riding for other team next year.
I also think the team is using some tricks that allows their riders to recover well in GTs, because it's a pattern for many years that their riders improve quite significantly in 3rd week.