Match results (wins and losses) affect your Elo based on a standard Elo calculation that takes opponent Elo into account. You have a separate Elo for each position (ATK, MID, DEF, GK).
Card Stats
Card stats correspond to Elo values, where the highest Elo of all players corresponds to a stat value of 80. The remaining 19 points per stat can be earned through XP. It will take a while for cards to calibrate, but eventually the stats will be strictly skill-based.
OVR & Position
Your card OVR is calculated for each position based on a combination of the rating stats. Each specific position uses a different combination, and the highest one determines which position your card is assigned to.
XP
You earn 2 XP for each tournament win, up to a maximum of 112. This is enough to set all base stats to 19 once maxed out.
Tiers & Preferred Position
Card tiers from Bronze to Elite are assigned based on OVR. Setting a preferred position in the stats editor increases your chances of being assigned that position in matches.