Often times the casual PvP doesn’t feel very casual at all. Teams can be equally as hard as what’s offered in ranked PvP, and/or the offerings can all be higher levels than me.
I suggest something like, in order to keep casual casual, the first spot is no higher than 1/2 your hero’s level, the middle spot can be between 1/2 to equal your level, and the third spot can be whatever.
Or the middle could be between 1/2 and 3/4 and the third spot 3/4 and equal.
I mean, it is supposed to be casual right? Well it’s not casual when it’s equal to, or worse than, the options offered in ranked PvP.
Casual is more a direct opposite to Ranked, meaning it’s PVP that doesn’t affect your ranking in the PVP ladder. It doesn’t necessarily mean it’s easier, you just don’t have to worry about losing points on the ladder. Also I believe your difficulty setting you have set on your world map DOES affect your PVP opponents in Casual PVP (but of course not Ranked) so if you have that set higher than “Normal” you might end up with more difficult matches)
Also Hero level is not a good indicator of your opponents power. While Gem masteries do play into a team’s Team Power, the bigger effects on it come from Troop Rarity, Traits, Level, and Kingdom’s at level 10/5-star. It is in theory possible to get a very high team power at a lower level due to either luck from chests, guild rewards (souls and gold mainly), or things like the new Path to Glory and Growth Packs.
Basing difficulty off of Team Power though is another issue entirely which is something that’s been struggled with even in Ranked PVP. The issue being WHICH team’s power do you base it off of? Since you’re given your opponent choice before you pick your team in both Ranked and Casual. The only static team you have is your defense team, and whether it should have any bearing on what kind of opponents you face has been hotly debated in the past. (very easy to manipulate by just putting a single low level troop on defense).
If you’re wanting something easier than PVP then maybe consider Explore at varying difficulty levels (depending on what you’re looking for challenge wise)?