For wrestling you have to qualify a spot for your country by winning certain tournaments during the year. Track should have this be part of their qualifying methods. They sort of do for the marathon, if you finish high in a WMM race you're auot qualified. They could extend it to track. If you place top 3 at world indoors you're auto qualified for outdoors. If you place top 2 in a diamond league meet you're auto qualified. And then define a couple other races on each continent that if you win them you are auto qualified. There will be some people who take multiple of these auto qualifying spots, so maybe only a dozen people qualify through this method. Then you can select the remaining competitors by a combination of descending order of top performances and descending order of rankings.
Only going off top performance list is not great because someone could typically not perform well but one time they had the stars align in a fast race that they don't even win. Rankings are flawed because sometimes races award big bonus points even though the competition wasn't actually very good. Doing a combination of multiple methods of qualifying would make people race more and try to qualify by multiple methods.
If it's only by ranking, they'll only go to the races they think they can earn bonus points. If it's only time, they'll only go to special time trial races. If it's only the designated auto-qualify races then they'll only go to those types of races.