Ballmer was Gates’ business guy, much like Tim Cook was to Jobs.
If you want to see the future of Apple under Cook, look at how Ballmer ran Microsoft: grew the valuation and stock price rose, while product innovation and quality lagged.
Totally unfair. The Ballmer years at Microsoft, from a product standpoint, were horrible. Cook is doing an infinitely better job.
Hardware-wise, Apple's product quality is not lagging. Software quality has been getting spottier for years, but I also think we have a tendency to see the past through rose-colored glasses. Bugs have always existed and I'm not convinced that Apple's software is truly any buggier today than it was 10 or 20 years ago when you consider how much more complex everything is today. We're definitely far less buggy than during the Classic macOS days!
I also think it's quite unfair to say that innovation is lagging. Apple Silicone is a huge innovation. Whenever I see people complain about Apple not being innovative, I have to ask who is more innovative in tech today? What company is producing more innovative products? I also think a lot of people have a tendency to view Apple and Jobs as, frankly, more innovative than they were. It's not like every product under Jobs was a massive innovation.
Apple has essentially had three truly Earth-shifting innovative products, the Mac, the iTunes Store, and the iPhone. The Mac changed the desktop computing paradigm, the iPhone changed the mobile phone paradigm, and the iTunes Store revolutionized buying music (and paved the way for the digital media economy in general).
Everything else has been an improvement over what already existed in the market. Some of those things, like the LaserWriter, were HUGE improvements, while others, like the iPod, weren't quite as huge, but successfully addressed the biggest pain points in the product category. MP3 players existed before the iPod and the iPod didn't radically change the MP3 user experience in the way the iPhone changed the mobile phone experience. The iPod did, however, address the major shortcomings with MP3 players and that made it a huge hit.
Under Cook's tenure, we've seen the Watch, AirPods, HomePod, HomeKit, ARKit (and the upcoming headset), Apple Silicone, Apple Music and other services, as well as massive overall improvements to iCloud. I don't think Apple is any less innovative under Cook than it was under Jobs. Jobs was, however, a much better showman.