Pixar was founded in 1986. They started releasing theatrical films with Toy Story in 1995. Are you really saying there hasn't been a single good Disney animated movie in the past 25 years? What's the basis for that statement?
The history of the two studios is way more involved than what you're suggesting, and talent moves around between studios quite a lot. And 25 years is a long time; there have been entire generations of talent that have risen up since then, and trust me, they're not all at Pixar.
Source: I worked at Disney Animation for nearly a decade (and closely with Pixar during that time). I'm certainly not unbiased but probably way more informed.
The history of the two studios is way more involved than what you're suggesting, and talent moves around between studios quite a lot. And 25 years is a long time; there have been entire generations of talent that have risen up since then, and trust me, they're not all at Pixar.
Source: I worked at Disney Animation for nearly a decade (and closely with Pixar during that time). I'm certainly not unbiased but probably way more informed.