Good question! It’s a mixture of both. The main goal for the model is to work out how good the starters and specs are in high-level play, so limiting things to tournament results seems the best way to do that. It also meant I could go back and capture all the historical data without going insane.
If I went back to add casual matches, I’d want the process to be automated, and that’s not easy to do for forum threads, as opposed to a digital version: the end of the match needn’t coincide with the last posts in the thread, or there may be a finals thread where the last two players play several matches without starting new threads, or people occasionally do follow-up casual matches in the same thread, or people misspell their own name in the thread name, or the thread name gives the wrong decks, etc. If a digital version appeared, a lot of these problems disappear.
What wouldn’t disappear is that occasionally I need to make a judgement call on whether a match should be included in the model: matches won on timeout aren’t currently included, but I also exclude matches by marking them as a forfeit, for reasons that can’t always be generalised. For example, this match is a clear candidate for removing, since skiTTer resigned on turn 1 when she saw she was facing Nightmare, so it has no information regarding deck strengths. More subjectively I’ve also excluded a lot of one player’s games (petE), because they realised they’d been playing incorrectly since they’d joined.
I don’t know how much it would affect things to add casual match data too, but see the monocolour matchup plot for Metalize’s data three posts up to see what sort of effect it might have.