What is the definition of a rover being used? I think there are very few true rovers in the league and not sure I would classify many of our guys as one.
The definition of a rover may differ slightly from person to person. My personal easiest summary is that it is a dman who is willing to be defensively responsible, yet still impossible to predict where he will go on the ice on any given play.
You know those hockey dome games and the player is on those tracks? I feel like most players actually kinda do majority play like they're on tracks. Rovers don't really follow the tracks at all.
Personally, IMO, if you look at the ozone as a 2 x 2 grid, a rover goes into all 4 zones vs a offensive PMD going into 2 or 3 out of 4. Part of this is that a rover may often enter and exit the ozone in a "U" shape vs a typical offensive minded dman may more habitually go with a "J" shape and go back to his side. You also need a specific skill set to be a rover with no rover capabilities seemingly possible without good skating and offensive acumen/skills.
A rover also is the first to enter the ozone/attempt to enter the ozone in the first wave with the puck with relative frequency as well and often one of the first entering the dzone no matter how deep in the ozone in the play prior to the reverse momentum.
A good d partner has to be able to actively determine the best option for being on the left or right side of the top of the blue line if the rover goes in deep. This is a challenge for a d partner already to cover both left and right ozone exits to reduce the efficacy of an odd man rush in the opposite direction, let alone a full system due to the fluidity of the options and risks that comes with aggressive offense attempts by a rover.
At least that's how I define it in my head.