The odd thing isn't about not having enough keys. It's about having no problem getting chests.
Inherently, it's not about playing good with any given champ. The most positive and game-influencing gameplay does not necessarily get you chests. If you play a champ with no regard to teamplay, you definitely can get a slightly more sizeable number of chests, but that doesn't mean you'll get honor.
I get/got a key fragment every game or two once I hit Honor 5 and kept getting honored, then sometimes got capsules with 2 or more fragments. At 13 keys and 2 fragments, I've gotten an okay amount of chests, but fragments just keep raining down.
I'm not saying you're not playing a champ well, only well in regards to how the system likes to score you.
Nor am I saying you're playing dishonorably, only that people might not honor you as frequently as the system likes to give you the obnoxious amount of keys that some people are getting.