I wouldn't call Motorola a failed acquisition - Google bought Motorola as a shield in an increasingly litigious environment: this was the age of Apple going "thermonuclear", Microsoft and patent trolls were wantonly shaking down Android vendors, and beginning to circle Google itself.
Motorola (under Google) had the best value-for-money smartphones - their midrange was solid, and reasonably priced while everyone else was continuously shifting to flagships, with each release priced higher than the last.
From the outside looking in, Google appeared to dispose Motorola to make Samsung happy - Samsung had been complaining loudly and widely about the Motorola acquisition, and openly flirted with other mobile platforms as a hedge.
Motorola shareholders got paid, Google got the patents it wanted, Samsung remained the 600 lb gorilla in Androidland, Lenovo got a good brand and keeps making ok phones to this day. So, not a failed acquisition by any reasonable measure
Google was searching desperately for revenue diversity and was acquiring pretty hard at the time. I think the intent with Moto was to acquire a hardware shop and establish a market leading brand to compete directly with Apple. They eventually arrived at Pixel by building it entirely in-house. That Moto got raided for IP and spun out to Lenovo did not meet those (high) expectations. There was no need for anyone to take a loss but I think Google wanted to make a whole lot of money and did not.
1. It was a crazy time. The winning consortium - which included Apple and Microsoft - invited Google to join their $4.5B bid; which would have made the patents entirely useless as a defense of Google against Apple or Microsoft. Google wisely declined, but bought Motorola less than a year later for $12B. https://www.theguardian.com/technology/2011/jul/02/google-pi...
Source: I was supposed to run the dogfood program in the NYC office. I never got the watches, but somewhere I still have the USB extension cords and the (then quite fancy) chargers with dual USB ports, one for your phone and one for the watch.
And they still do under Lenovo. Multiple-day battery, almost stock Android with very useful enhancements.
I was hopeful for the post-acquisition Motorola but it didn't quite pan out. The IP salvaged from the purchase was always a big part of the deal so it wasn't really a loss, just not really much of a win either.
I have an iPhone mini now, but it's still not small enough to 100% operate one-handed, at least not without grip adjustments. The Moto X wasn't quite a flagship phone, but it came close enough. I can't even find a properly one-handed phone anymore
Eventually the Moto X came along. I thought it was the perfect phone. Its voice assist features worked better than most voice assist features even today. You could easily do everything you wanted to do with the phone in your pocket and your earbuds in.
It had the perfect size screen. It had a great ambient-on watch-face screen that looked nice sitting on your desk among clutter. The dimple in the back was a really nice touch, it made it like a worry-stone[0] in your pocket. It had a lower resolution, but I kinda liked that about it. I think Motorola was bought or something, but whatever the reason, the next phone in the series ditched everything single thing that made the Moto X special.
Those two devices were both my favorite mobile computing devices, and probably the closest I've come to getting fan-angry about a company screwing up their own magic.
More to the point: you might have been able to see it at Motorola, but even looking back, I don't understand why Razr couldn't have won against the iPhone. The Razr was a surprisingly capable little machine!
[0] - https://en.m.wikipedia.org/wiki/Worry_stone