6lennn: I guess I'm asking whats more important at my level, the average score or the XP
First off, some tourneys like that Championship are not a convenient floor for lower tiers, because the conditions are equal for all which means a disadvantage for you, lacking perfect equipment.
Second, a bad result may influence your average but it won't "destroy" it, due to the calculation mode - look up "saturation".
The loss in XPs for quitting one game would be marginal, 400 for the tourney plus 1 for each stroke that you didn't play. You'd gain the CDP nonetheless.
Concerning "importance", levels do not matter and tiers do not matter, IMHO.
What matters is that you have fun in the game, FUN!
Starting from that, you may waste a thought on what kind of fun you want to have
- any idea?
And if you are determined to follow the visible "goals" of the game, be prepared for perpetual grind.
Levels will spread a lot(!), e.g. 10x your status for L74, 100x your status for L95, just to grant you WGT's permission to buy some coveted equipment.
Tiers will require you to play more and more games for saturation, from 25 for Tour Pro to 500 for Tour Legend (that's not the end!)
CDP (continuous days played bonus, a major benefit to level up fast) will need daily engagement with the game, and nobody but you will see the result!
(I won't pick up the questionable hysteria around the Clashes)
You might as well be a happy camper by playing the odd game every now and then, enjoying the scenery, make friends for matches + friendly banter, or a lot of other online activities.
Your choice!