Over at “The Sky Full of Dust” they’re designing an RPG! It looks like a fun project. Mr. Forster has started his exploration of rules by poking at stats. I think he might have things a bit backwards, however. Yes, stats, if you chose to use them, will form the bedrock of your game and its mechanics. But, exactly because of the central place of stats, you might want to leave them as the last thing you nail down solidly.
A more current theory about the battle says that the deciding factor was matériel, the Norman use of combined arms and mobility versus the Anglo-Saxon static shield wall. This is a much more tactical view of the battle, in which the placement of troops, the layout the terrain, and individual unit statistics become vital. Balancing the resilience of the shield wall, the long-range harassing affect of archers, and mobility of cavalry in statistical form is central to modeling this sort of battle.
But there is also a third view of the battle. At one point in the fight, word spreads that William has been slain. Hearing this, William removes his helmet to show his fleeing warriors that he is in fact alive. His soldiers rally, and William notices that parts of the until-then impenetrable shield wall had broken loose to chase his fleeing soldiers. The shield walls quickly reformed, but it gave William a clever idea. After a few more feints, his soldiers faked being routed. Sections of the shield wall broke off to chase down the fleeing Normans, but were themselves surrounded and wiped out by prearranged ambushes. With the shield wall fatally compromised, the Normans are able to chop it up and wipe it out piecemeal.
The same holds true for RPGs. A game about slaying vampires and finding a date for prom ought to have very different stats from a game about exploring dungeons. Mr. Forster has decided to limit himself to just three stats, boiling them down to only those immediately useful in combat. But now what is he going to do about adjudicating those abstract languages rolls? Does everyone have the same chance of knowing a language? Or is it based on class? I could certainly see reducing things down to a single stat measuring mental strength which would handle learning languages, resisting spells, and similar issues. But if he's making the game I think he's making, there's a good argument for stats beyond those used in combat.
And what sort of combat does he want? To-hit rolls and hit points work great, but they're not the only option. What about a combat system based more on unit tactics, shield walls of hirelings or hired goblin skirmishers? In that sort of the game, charisma could be far more important than individual stamina. On the other hand, a game in which combat is specifically designed to only take up a limited number of decision points might not need hit points at all. Instead, the vital combat stats might be which schools of combat your character has mastered (di Grassi versus drunken boxing or somesuch).
You can start with stats and have everything flow from that. But to my mind, it makes more sense to decide what sort of structures you want in your game and then design your stats to support those. The stats are the bedrock of your game, and as such, go a long way to not only defining what the PCs are like, but also what your game is about. Having a solid idea as to what both the players and the PCs will be doing in an average game session can go a long way to helping you decide which stats you need.