Adopting scrum is subjective

I have experienced that "scrum is subjective to the teams" in my current project. I am working on an existing legacy java application. I am part of a scrum team of 10 people. We are termed as one of the high performing scrum teams at my company. Our client is so pleased that they want to retain the same for another project :).

But when I tried to analyse our success, I realised that we never followed scrum 100%! Following are the things that make me believe so:-

• Sprint backlogs did change during the sprints. Team was able to accomodate new stories and deliver value addition. There were many sprints where we could deliver extra credit stories.
• Team used to skip standup calls on days when team(onsite+offshore) didn't have much updates/risks to share.
• Since we were working on a legacy application, the team's estimates were high during the release planning due the less acquaintance with the application. But as we spent more and more time on the application, we were able to revise and reduce the estimates. Once, we changed the estimates during the sprint!!

Following are some of the things that we didn't do and saved time.

• Never created a release burndown chart
• Never created a sprint burndown chart
• Never tracked individuals' hours spent on the tasks

So I feel team should be empowered to decide what works for them and what not. They should alter the scrum in a way that works best for them. I have seen teams with 100% adherence to scrum but performing poorly in terms of the development and delivery.

Any thoughts??