Manufacturer's Promise is there to tell us if the C-Rating of the LiPo pack is actually accurate.
Based on what the Manufacturer claims the pack is capable to deliver, we calculate the actual C-Rate based on the worst cell's Internal resistance.
The relative number out of there tells us how good the C-Rating of the Manufacturer is.

• MP == 1: Very good. The proclaimed rating matches the mesured one
• MP < 0 : No good. The LiPo pack delivers less than claimed
• MP > 1 : Excellent - The LiPo pack delivers more than claimed