No, there's plenty of details about the boardroom coup attempt, Sculley even alludes to a showdown. You can keep trying to fit it into a narrative of simply being focused on results, but there's plenty of information out there on this issue, including Jobs arranging a boardroom meeting on Sculley's planned trip to China, and how Jean-Louise told Sculley of Jobs plans so he could cancel his trip and fight off the coup attempt.
Sculley got rid of Jobs because Jobs, a 15% shareholder and chairman of the board, was trying to get rid of him.
Sculley likes to say many different things in hindsight, here's another, which indicates it was about a power struggle:
http://www.thedailybeast.com/articles/2010/06/06/why-i-fired-steve-jobs.html
A basic chronology:
1. Jobs has poor results, primarily with one product, over a relatively short period of time.
2. Jobs defends his stances in spite of short term results. Sculley disagrees and believes kneejerk reactions are necessary.
3. Sculley and Job cannot reconcile this difference so Sculley moves to have Jobs fired.
4. Instead of firing him outright. The board agrees to relegate Jobs to a token and powerless position. They literally relocate his "office" to an abandoned building nearby.
5. Jobs gets upset about this and tries to get rid of Sculley.
6. Jobs appeals to the board. They dislike his short term results and side with Sculley, allowing him to fire Jobs.
7. Several years later the board also fires Sculley after he has a bad year.
You're focused on exactly #3. It was a chain reaction started by knee jerking over short term results and ultimately concluded with a justification based on short term results. The "power struggle" was Jobs disagreeing with the obsession over short term results, and short term results winning out.
Interesting link though. Gives you some real insight into the type of people that make up these boards:
Board member Arthur Rock, a venture capitalist who helped found Intel, among other outfits, dubbed Jobs and his co-founder Steve Wozniak as very unappealing people in the early days. Jobs came into the office, as he does now, dressed in Levis, but at that time that wasnt quite the thing to do, Rock told a little-noticed University of California, Berkeley venture-capital oral-history project. And I believe he had a goatee and a mustache and long hairand he had just come back from six months in India with a guru, learning about life. Im not sure, but it may have been a while since he had a bath.