Sales can often be attributed to how good or bad a game is.
But even good games can struggle to find an audience. (And I'm not suggesting Concord is good btw.)

At VGChartz we have the original Persona 3's sales listed at 0.45m units worldwide.
While Persona 5 is selling many times more than that. (The total combined sales between all versions surpasses 10 million.)

Is Persona 5 that much better of a game than Persona 3 that it went from being niche to very popular?
Not really. But P5 managed to market itself better.

Same can be said for franchises like Nier and Yakuza. Their audience suddenly grew many times over with Nier: Automata and Yakuza 0, even though they didn't really change their formula.

*Cries in Titanfall 2*

WHY RELEASE IT BETWEEN COD AND BATTLEFIELD.

This is sort of an issue Concord would have either way, it doesn't matter that Overwatch and the others aren't new releases, they're continuously updated videogames with millions of people still playing them, they're F2P and Concord is expected to try to pull players away from these games at a $40 price tag, it is not competing in the sense of release schedule but it is competing for players valuable time.

I want to push back on this.  I think the cream of the crop always rises to the top - rarely later than sooner.  If a game doesn't catch on/sell well, it simply wasn't good enough.  I will admit there's some cognitive dissonance here; I loved Pandora's Tower but it sold shit and will be memory-holed in gaming history BUT... it just wasn't good enough.  I don't think there's ever a "good" reason an excellent game flops.  

Tin foil hat time.  Total planned move by EA - crush Respawn into dust and absorb them like the vacuous monolith it is.

It was actually for once not EA's fault, Lmao.

Pandora's Tower wasn't a well received game. 

Would you say that Farmville is peak gaming? At one point that was one of the biggest games, tens of millions of people were playing it daily on FB and elsewhere. 

I'd argue most of the most critically acclaimed games did not do amazing relatively speaking. The big exception is GTA. That's pretty much the only time where the biggest selling game happens to be one of the most critically acclaimed. Super Mario Galaxy is outsold by plenty of games. 

Ico and Shadow of the Colossus are very famous in the industry, they frequently get credited by game developers as inspiration, and yet they both sold very poorly. 

Great games usually do well, but there's definitely not a 1:1 of doing well and selling well. There are some games that are very beloved and yet poor selling. And some games that are kind of hated and yet sold well.  

There's a million reasons that affect how well a game does. How good it is, whether that concept is really appealing to a lot of people (Wii Sports was extremely appealing to tons of people, but I don't think most people would say it was the quintessential gaming experience), whether that appeal is marketed, whether the market is interested (I don't think Demon's Souls/Dark Souls was an interesting concept for the market when it came out, but the fanbase has grown substantially).

Arkane Austin lost more than half of its studio during Redfall's development because nobody wanted to work on the game, and that was before Microsoft purchased Zenimax. While I'm bummed that Arkane Austin closed, was hoping for Dishonored 3, it was going to take who knows how long before the studio was going to have the number of developers it had when it released Prey. 

Concord on the other hand seems all the developers really enjoyed working on this game, so it makes the games flop all the more heartbreaking.

Well I think that's different.  Games can be successful while not being great.  Madden games are copy/pastes of the same game every few years and they top charts every NFL season.

I'm commenting on games being seen as "great" and not selling. If it was as good as we think, it would have sold as good.

You're right, Pandora's Tower doesn't fit the archetype and was just a personal example, I personally loved it but I understand why it wasn't well received.

Well I don't know what your definition of not catching on/selling well is. I think some of the publishers of the aforementioned francises were happy with sub 500k sales for their games at the time, and considered selling well. But the exponential growth in sales for some established franchises I don't think can be attributed to a quality difference between the games.

Rather than selling good or bad, I'd phrase it as its ability to reach its target audience.
An audience that was there and would have liked the games, but didn't play them.

That can include franchises that already sold well, and then suddenly sold many times better.

Fromsofts Soulslike games were all well recieved critically acclaimed games that sold very well. Sekiro won Game of the Year, etc. And their multiplat games all sold around the 10 million mark for over a decade. It looked like there may not be much more possible growth for the series. But then Elden Ring sold 25M+.

I don't think it being open world explains such a dramatic growth in sales.

Another example is Among Us. While it clearly also benefitted from the Covid situation, we can rule out any difference in quality affecting its surge in popularity. It simply got more exposure from some popular streamers playing it a few years after launch, and almost overnight exploded in popularity and became a huge phenomenon.

Products like Concord need to fail so studios can get back to creating games people want. This is good news.

It's exactly what explains the jump in sales though? People like large games and exploration.