The actor said his age at the time put him in a weird position, as he was somewhere between playing a teenager and being the dad.
"I never looked young enough to be in high school, even when I first got out [to L.A.] and I was 25, so I missed out on all of the 'Dawson's Creek' and all the early WB shows," he said. "So then they were like, 'Come play one of the dads,' but I wasn't old enough to be that, either. I had to wait around a long time."
That waiting paid off big time, of course, as "Mad Men" became a massive hit and won him an Emmy Award and two Golden Globe Awards for Best Actor.