Yes, the episodes where they team up with the borg is the time 7 of 9 becomes part of the crew, and Kes is gone...
She was brought in as eye candy but along with the doctor ends up being one of the most interesting characters on the show. I've been rewatching a bunch from the last 3 seasons this week, the only characters that become fully 3 dimensional are 7 and the doc, B'Elanna and Neelix grow a little, but the rest are all pretty much exactly the same at the end as they were in episode 1. Really bad since there are one off episodes where they do grow, but it's all forgotten by the next episode. And the time travel episodes where we see older versions of them show that the actors were capable of becoming more complex, so the issues with Voyager really can be blamed on the writers.