Good was a very relatively word.
Yes, the definition of it was a very clear cut one but when you tried to translate into real life something didn't fit. Mainly because 'good' it's always defined by the person that's using the word rather than the word itself.
It took Ward only five years to realize that he might not have been a 'good person' by Coulson's standards and therefor not 'good enough' for Skye but that didn't mean he didn't have anything good left inside of him. Because he did. He did and he was hell bent to prove to everyone and most of all to himself that he could redeem himself.
Grant Ward was going to make up for every single bad thing he did and in the process maybe redefine what the word 'good' actually meant.