Various criteria, such as number of wins, UCI points, are good for comparing GC contenders and sprinters. Climbing times and wattage can say a lot about quality of a climber.
But quality of domestiques is a very important factor in order to achieve team's objectives in any race, too. I am not able to think of some (at least partially) objective criteria to evaluate domestiques.
- Are there some criteria by which performance of domestiques can be rated?
- Are there some websites which give rankings/ratings of cycling domestiques?