As conventionally understood, a Bland-Altman analysis is for testing the level of agreement between two different ways of measuring the same thing. See, for example:
http://www.stattutorials.com/SAS/TUTORIAL-BLAND-ALTMAN.htm
https://en.wikipedia.org/wiki/Bland–Altman_plot
https://community.jmp.com/docs/DOC-6171
So using this approach doesn't seem to stack up with your desire to 'analyze how far each trial is away from 0.667'.
Can you describe a little more how your data was measured, or better yet, supply a sample?