Particularly when designing archetypes and ensuring they are supported, the player and designer roles get mixed up easily. The designer just wants to provide the player the tools they need to be able to draft the archetype. This, plus the powermax philosophy (always replace a card with a better card), makes a lot of cube designers get used to wearing the two hats at the same time. There's also the fact that people are used to being deckbuilders, and they treat building a cube as an extension of deckbuilding.
It's not too different a mindset when an archetype is being built from the ground, or needs to be strengthened, but for all other situations, thinking as a player and as a designer should be two very distinct processes.
The most important distinction is what you are optimizing for.
As a player, you're mostly optimizing your deck's win rate. In any (2-player) cube, the average of deck average win rate is 50%. That's not the point for the cube designer.
The cube designer should optimize for fun, whatever that is to you and to your playgroup.
A player doesn't usually think much about "what makes games fun". A game and cube designer's most important task is answering this question. I'll bail out from debating what "fun" means here, and treat it as this abstract, magical metric too. I'll try to write something longer about what I think people find fun in Magic and Cube, but for now, I'll just list the main aspects I've been trying to optimize and balance in my cube, each of which I believe to either translate into fun or avoid problems that get in its way:
- Agency: how much a player's decisions influence their win rate.
- Resonance: how familiar the game's concepts are to the players.
- Elegance: how easy it is to grasp what a card does, and how easily it does it.
- Variety: how different the player experience is from one draft to another and from one game to another.
- Stability: how much knowledge players keep about the cube from one session to the next.
A practical example
When I, as a player, think about whether it's worth replacing Watchwolf with Fleecemane Lion, it's straightforward. It's better. If I have the card, I replace it. If I don't, I consider if the price difference is worth it. When I, as a designer, consider the swap, I have to think about all those aspects:
Agency: Fleecemane Lion has an activated ability, and though the choice of activating it or not when it's being targeted is easy to make, whether to leave mana up for it, or whether to activate it mid-combat and open yourself for removal is an interesting choice. On the other hand, depending on removal quality and creature sizes, the opponent might less agency if they can't deal with a Fleecemane Lion because of hexproof and indestructible. This is a mixed bag, and I personally count it as a negative for the swap.
Resonance: Fleecemane Lion is a reference to the Nemean Lion (
https://en.wikipedia.org/wiki/Nemean_lion), and people who get that reference will immediately grasp why the card works like that. People who don't will probably have to memorize the card, but one day, when watching a random Youtube video about Greek Mythology, it might just click. I don't really understand Watchwolf and couldn't find any lore references to it. I count this is a positive change.
Elegance: Watchwolf's obviously simpler, and what the card says without any words is "here is a reward for playing Selesnya and fixing mana, you get to play ahead of the curve." This is pretty elegant. Fleecemane Lion says the same thing, but also "... and here's a subgame: you get to make this immortal for five mana, but your opponent might kill it in response." It uses a set mechanic and two evergreen mechanics to do that, and a counter with a state change that's mostly represented by the counter, but not exactly. It's pretty inelegant, though if you know the greek mythology trivia the resonance largely offsets this. Still, the swap is a clear negative in elegance to me.
Variety: At lower power levels, the game becomes about Fleecemane Lion, reducing the variety of gameplay. Also, it may be an auto-include for decks that can support its mana cost, and auto-includes reduce variety of decks. At higher power levels, this would be a positive actually, because Watchwolf would be unplayable, and something that moves the maindeck rate towards the average increases card variety.
Stability: Learning a new environment is daunting. To be invested in an environment, players need to have some stability, so that the cards, combos, tricks, archetypes, and everything else they learn in a draft carry over to the next. This change would be beneficial if Fleecemane Lion was a previous holder of the slot, but is a negative one otherwise, and very negative if Watchwolf had been in the list for a long time. Yes, this is a reason to keep sacred cows in a cube.
I took an example where it's very easy to decide for the swap as a player, but most of the time cards that aren't strictly better, and being a player/deckbuilder is more interesting than I described. Still, the breakdown of what aspects you should consider as a player (can you mana base support it? Is it good when lagging behind? Is it terrible against agressive decks?) are a subset of the aspects it's useful to think about as a designer.
And that's why designing cubes is hard and awesome.