Last weekend’s Mt. SAC Relays were the first in more than 20 years not to feature masters. In the late 1990s, when I first started covering geezer exhibitions at Walnut, we had an age-graded 100, flat 200 and age-graded 800s — with National Masters News publisher Al Sheahen calculating distances and starting times (for the 800s). Masters also ran 110 hurdles some years and threw the hammer. But in recent years, especially in the men’s and women’s 800s, few runners showed up. Some races had only two or three entrants. Scratches weren’t a problem for the sprints. But the writing…