Yes. You have class imbalance. You have classes on the 'wrong' side of that imbalance (tho, really, the OP class could be nerfed, too). Yet they are still popular. If they weren't played at all, they would just be wasted space, since they are played, they're succesful trap choices.
I don't believe there is a right and wrong side of balance. There is a strong and weak, but what is right is what you as the player want to play.
Being weak is not the same as being a trap, nor is it the same as being wrong. I am playing a Monk right now, I was not trapped into doing that and I am not wrong for doing that.
I suppose sub-classes do cover a range, too. You could look at that different ways. You could consider each sub-class independently, which is not unreasonable. Or you could consider each class, either, as a whole, or before considering sub-class (or considering it's 'best' sub-class if they're not balanced), since they are equally-weighted choices. Then consider each sub-class only with respect to other sub-classes of the same class.
This is a flawed approach because certain classes are more reliant on subclass than others. Wizards and Paladins for example are not heavily reliant on subclass. Clerics and fighters are more reliant on subclass and subclass is a
If you consider the best subclasses of each class (probably Rune Knight or Eldritch Knight on a Fighter), the amount of imbalance goes down tremendously becuase that is a big buff for classes like Fighters and Clerics, but a smaller Buff for other classes. Further using an optimal class for some classes like Cleric (Twilight) or Monk (Mercy) completely changes the dynamics of the class Balance. A Twilight Cleric more powerful than any Wizard with equal abilities at most levels if you do it this way. So to achieve "balance" you would need to actually nerf the cleric or buff the Wizard, since the optimal Cleric is so good.
Further the amount of imbalance between fighters and Wizards is generally small compared to the amount of imbalance between races when playing such classes and the best races typically do more for Fighters than they do for Wizards.
So when we are doing this balancing act are we assuming optimal races too? This is important because the best races are a bigger boost for martials than they generally are for casters. So to achieve this perfect balance are we to assume the optimal race for each specific class (and subclass). So there is one single point where there is balance?
What levels should we strive for balance at? Wizards are not as powerful as Monks at 1st and 2nd level, so do we need to nerf Monks a bit because of that?
Finally different ability scores dramatically change balance and not only different ability scores between PCs, but the same distribution on different classes changes the balance dynamic as well. A Wizard with no ability above 14 loses a lot more than a Druid with no score above 14. A Paladin with a single 14 who picks an optimal subclass is generally going to be weaker than a fighter with a single 14 who picks an optimal subclass.
Any two classes should balance.
You can't do that as long as choice is at play. My fighter that chooses to invest points in Charisma instead of Constitution (and this is common on fighters I personally play) is going to be weaker.
Imbalances among martials are a blip compared to those between full casters and non-casters.
The imbalance between Fighters and Monks at most levels is larger than the imbalance between Fighters and Wizards at most levels. Where this is not true are levels 1-2 where the Monk is actually the most powerful of these three classes and at level 17+ after Wish comes online. At every other level a Fighter is closer to a Wizard than it is to Monk.
Which is not to say they're minor, just that the martial/caster gap is huge.
Not at all levels and especially not if you assume optimal subclass choices.
There is no appreciable gap between an optimized human fighter with standard array at levels 3-8 and an optimized human Wizard with Standard Array at those same levels.
TBF, a first step could be determining which class has the least leeway in setting it's overall effectiveness. In D&D, that really seems to be the fighter, which is constrained by a profound unwillingness of vocal enough segments of the fanbase to accept it as supernatural, and another equally small and vocal segment even less willing to accept non-superntural classes being able to do much.
No it isn't, it is the Monk or Barbarian at most levels above level 3 and the difference is pretty great.
This argument that fighters are restricted to being mundane holds no water at all in modern RAW 5E considering all the supernatural options available to fighters.
The fighter has very strong subclass choices it can use to set overall effectiveness, including access to spells and many other supernatural abilities through those subclasses.
Fighters can turn giant size and summon flaming shackles or teleport across the battlefield, or have poisonous thorns spring from their arrows, or shoot fire from their fingertips ..... It is fine if players choose not to have their PC fighters do those kinds of things, but it is also a conscious choice to play on the weak (but not wrong) side of imbalance.
Once you've done the best you can with that class within those constraints, you could nerf or buff other classes to it's level.
But those aren't constraints in 5E. There is no requirement at all for 5E fighters to not be supernatural! Aside from the subclasses and races, in 5E not even the feats are constrained like this.
If I want I can build a single-class fighter that can cast 14 leveled spells a day at 8th level. That is without even thinking about it very hard!
