One of the coolest and potentially time-saving tricks available in only to Moodle 2.8 is the capability of importing grades by just copying and pasting them from Excel. The feature is briefly mentioned in the Gradebook Overview for 2.8 starting at about 3 minutes in: direct video link https://youtu.be/CMXvtFPmd0o?t=3m6s.
In order for this to work you just need to make sure that you have the correct field headers selected along with the user info and assignment grades for each student. Note that you’ll want to only import data for students with actual grades (no value for a grade could still cause an override [identified by a change in color] for those student grade items).
Read up on the easy to follow steps at https://docs.moodle.org/28/en/Grade_import#Paste_from_spreadsheet
Pretty slick usability enhancement. Check out the full video for Gradebook enhancements in 2.8 here or below: https://www.youtube.com/watch?v=CMXvtFPmd0o