"Auf Deck, Kameraden, all' auf Deck!
Heraus zur letzten Parade!
Der stolze Warjag ergibt sich nicht,
Wir brauchen keine Gnade!"
(Rudolf Greinz, "Der „Warjag“" 1904,)
Not all premium ships in WoWS are high-tier. There are also some pretty low-tier premium ships, sometimes given out as gifts or marathon rewards. Naturally, most of these ships belong to pre-dreadnought/early dreadnought era; such as the HMS Dreadnought herself.
Varyag, the Russian Tier III cruiser, is one of such examples. It is a moderately fast and moderately agile cruiser with a bunch of dinky guns and not much else; closer to St. Louis or Bogatyr. I suspect its addition to the game has more to do with the ship's history than anything.