[ChipMHazard]

Ah, the good old blame the players.
You did however fail to mention that Magriders are able to dodge incoming fire more easily than other MBTs the further away they are from each other. I highly doubt that a good Vanguard player will always win against an equally good Magrider player based solely on the Vanguard having the shield ability and dealing more damage. You have to be able to hit your opponent for your higher damage per shot to matter.
Making sure that when other tanks do hit the Magrider it hurst more, from the front, would be one way to handle it.

Both the Vanguard and Magrider have an effecient way to avoid taking damage, via the shield and speed boost/mobility respectively. Something the Prowler lacks.