Are men the new women?
This is totally unscientific, but I think men's sizes have started to go the way of women's.
Today, I bought a medium basic long-sleeved shirt made from a "performance fabric." Back in the day when I was actually performing, a medium t-shirt fit snugly but not at all constrictingly.
This shirt is not quite baggy, but let's say I could add another 20 pounds to the 20 pounds or so I've added to my marathoning weight before this shirt would fit me like a medium did in the old days.