In terms of quantity, 2015 is when they started churning out 2x movies per year sometimes. From 1995 to 2014, they had 14 movies over 19 years. They skipped years sometimes. From 2015 to 2025, they've done 15 movies in 10 years. And looking at the 2026 coming soon section at the bottom of the link, they got 2 more in 2026. And both are theatrical movies, not straight to streaming.
You might want to look at the years more closely.
First of all, it took Pixar three years after Toy Story 1 to make A Bug's Life. They obviously were still getting used to being time efficient with the technology. And quite frankly, if stuff like A Bug's Life (let's remake Seven Samurai with bugs!) and Cars 1 and especially 2 (let's sell toys! Now let's make them spies or some shit, who cares?!) is among those films of 1995-2014, it shows less output doesn't always guarantee consistent story quality IMHO.
Also, 2015-2025 would be a span of 11 years, not 10. Not a major difference, but still.
I already discussed how only two Pixar films post-2020 were actual theatrical films that underperformed. We cannot know how two of them would have done as they did not get normal theatrical releases thus only wild speculation can be made how they would have done theatrically.
If we're talking 2016-2020:
Finding Dory - 1+ billion on a 200 million budget
Cars 3 - 380 million on a 175 million budget (this is one where merchandise sales are very relevant, seriously, in the US, some toy stores would devote an entire aisle to Cars alone)
Coco - 810 million on a 175-225 million budget
Incredibles 2 - 1.2 billion on a 200 million budget
Toy Story 4 - 1 billion on a 200 million budget
Onward - 140 million on a 175-200 million budget, however this March 2020 film did not get to last long in theaters due to this being the beginning of COVID in many areas
Soul - 150 million budget, and was released straight to Disney + in December 2020, however when it got a theatrical release in 2024, it managed to make 120 million despite having been on streaming for three years by that point
So basically, we have one sequel (Cars 2) that did okay at best, and one original film, Coco, that did great, possibly Soul did great as well but it's hard to know for sure as we don't have exact streaming viewing figures of the film (if someone claims otherwise, triple check that shit, from my understanding, people claiming to know exact streaming viewing numbers of most films or shows are making shit up) though it's reasonable to say it probably did at least decently if it could still manage to make that much theatrically after three years of it being available on streaming. But ultimately, I would say Soul can't be fully ranked one way or the other, and this is especially true for Onward given its circumstances in March 2020. And the other sequels? Massive successes.
Post-2020, we have two straight to Disney + releases, so it's hard to gauge how they would have done with normal theatrical releases, two films, one original, Elio, and one spinoff, Lightyear, that did poorly, and one original film, Elemental, that did decently and one sequel, Inside Out 2, that was a MASSIVE success at 1.7 billion.
So I really think we're jumping to conclusions to claim after only FOUR theatrical films, two successes and two not-successes, that they've started a "hit or miss" phase in terms of box office, especially as shown, 2016-2019 definitely can't qualify as part of said phase. If the trend keeps going, sure, but it seems premature to call it such this early.