I just played a bunch of PVP matches, and I didn’t get a single human player. The bots are really obvious, they don’t have a guild, and they all play with the same bad AI that includes dropping a unit as soon as the game starts.
Do you win the games ? 
Thats no bug. That are Blizzbots and they always where in Rumble for the noob-ranks. Dont know what rating you need after the new PvP rework, but just level up and they will disappear (but you face LvL 11 whales instead and wished for the bots back HA)
With the new Victory Road system you will find real players starting to appear after you have reached over 9 to 10K honor in PVP.
Probably so everyone can gather all the Victory Road loot before real pvp starts.