The player can make max tier troops with the two Steward perks. The AI can't use those perks, because they never get loot from a battle, only gold, and they never buy gear from shops. The player can always have the advantage.
TW made changes to auto resolve, so you don't use just one type of troop to always win every auto resolve, like we could before. Your best bet is to use a variety of troops, at or near max tier. Tier was very important in the match ups, I haven't tested it recently. If you lose troops, replace them with recruits and donate gear to raise their tier.