Berto "overlooked" Ortiz just like Ortiz was "on something". Personally, I think Berto was and is a protected fighter that's imposed on boxing fans by a promoter and network in an attempt to create a star that just simply didn't have what it would take. The thing welterweight division never made Berto an A fighter by default, he's a B fighter.
Mayweather is nothing like Berto, Berto at times just put his back to the ropes and gave up rounds against Ortiz. The Berto fight for Ortiz is about as meaningful as the Margarito fight was for Mosley when going into a fight with Mayweather. This is just a very marketable in-house fight for Golden Boy Promotions to put on.