Stop being intentionally obtuse and I didn't say we draft OL better in later rounds. Teams, including the Saints, sometimes get lucky on OL in later rounds, but it's not a sustainable way to build an OL or a good strategy for building an OL. It's not like the Saints have some special talent for drafting OL in the later rounds, you need look no further than Rick Leonard.
The last good Later round OL we took was Armstead 11 years ago and he was taken in the 3rd round. The next was Carl Nicks in the 5th 16 years ago.
That's two good later round pick OL (if you consider the 3rd a later round) in the last 16 years. You can not build an OL like that. Even if you go further back and add Bushrod and Evans, that's 4 in 18 years.