Despite literal decades of Patsfans love of Welker and Edelman, the reality is that neither the SS nor the 3 cone are correlated with WR success. You can have a score so poor that it is unlikely you will succeed, yes. There is a small correlation between 3 cone and draft position, which shows that scouts as well as draft nerds likely overvalue it.
There is not a strong predictive correlation between a college wr and nfl success. The strongest, which are still quite weak, are draft capital, college dominator score, age at dominator break out, and yards per route run.
Age, height and weight are semi-useful, and if you had to pick one metric, it should likely be the broad jump