Silver Charm's response notwithstanding, which certainly happens, look at the TGI (Thoro-Graph Index, an average of tops run by the sire's runners in each category) for the sire. As a rule tbreds develop about 6 points from their 2yo top through their 4yo year and a point more for 5 and up. All levels of talent will run close to this average, the faster more talented horses will do it at lower numbers and the slower less talented ones will it t at higher numbers.

As Johnnym suggests look in the archives you'll be surprised just how solid this development mean is.

TGAB