Cisco has simply atrophied over the last seven years. When the board replaced one salesman with another salesman in 2015, it was clear that his only job at Cisco was to slow the rate of decline for as long as possible.
Other technology leaders from the 90s/00s retooled for the changing market (e.g. Nadella at Microsoft) and have recreated their past successes. Cisco's focus has been on ignoring their customers' changing needs and on continuing to sell the the technology they brought to market in the 90s/00s.