I'd like to report a few UX issues here with linking to a user's course grades.

1) First of all, the "Grades" link in a user's course profile leads to a page like:

/course/user.php?mode=grade&id=9&user=2

where it lands under an incorrect secondary navigation path - "Participants". 
The user cannot directly use the Grades menu / drop-down to switch to other views.

I think the "User report" page would be a much better direct target for the "Grades" course profile link:

/grade/report/user/index.php?id=9&userid=2

at least for the Student role course participants.
(I actually think the "Grades" link should NOT appear in the teacher course profile at all, since the teacher grades others in the course, and is not listed in the course's grader report at all.)

2) The same problem affects the generic Grades page /grade/report/overview/index.php (accessible from the user's menu top right) , where for the "Courses I am taking", the links also point to: 

/course/user.php?mode=grade&id=9&user=2

rather than to 

/grade/report/user/index.php?id=9&userid=2

causing the same confusion with navigation.

3) Finally, I think the "Grades" link should NOT be included on the users' FULL profile pages, since there are (usually?) no graded activities on the front page. The "Grades overview" link is all that's relevant in that context, IMO.