You have to have X average or below over Y number of ranked games. X and Y both vary based on the tier. Ranked games include multi-player and single player ranked stroke games, and tournaments of any kind, 9 or 18 holes. As you go to higher tiers (ex. Pro to Tour Pro), the average needed (X) gets lower as the number of ranked rounds (Y) gets higher. Level has absolutely no bearing on tiers, and match play, alt shot, CTTH, and practice also have no bearing on tiers. The averages and number of ranked rounds are undisclosed figures you can easily find elsewhere on the boards :p