Devops is a failure only when you have the wrong people on the job. Which is nearly all the time because only 1 in 20 engineers has the ability to do both operational and development work to a standard high enough not to put your organisation at risk.
If you have several of those 1 in 20 people they will self organise into a methodology which roughly resembles it.
If you have several of those 1 in 20 people they will self organise into a methodology which roughly resembles it.