I suggest you revisit the history of the first days of the invasion, specifically the depth which the ground armored forces reached in the first 2-3 days and what and how they were stopped. The Baltic states "width" is much smaller, and thus there is much less time to organize defense, etc. It is hardly enough time even just for taking the decision to initiate defense. Of course, like in the case with Ukraine, Russia wouldn't succeed if the quick invasion turns instead into a face-to-face war midway. That is why they are looking for a way to create blackout and chaos.