Dos Anjos has decent hands but they've become overrated after his fight with Cerrone who has awful hands and a serious lack of knowledge/training against southpaws. Seriously, Cerrone has an awful jab and in an orthodox vs southpaw match the orthodox jab is already inherently diminished. Cerrone was so unprepared or mentally unaware that he actually walked in behind his jab just make sure it landed in the 1st minute of his rematch against RDA and was immediately met with a left hook. It was the dumbest possible thing he could've done against any southpaw striker nevermind a competent one in RDA. In fact, almost everything RDA did against Cerrone was Southpaw vs Orthodox 101 type stuff. That fight means nothing to McGregor. I still can't believe Cerrone has learned absolutely nothing from fighting southpaws.
McGregor and RDA each have 3 or 4 fights against fellow southpaws, I believe. Look there for your answers and you might find some information relevant to your question if you know what you're looking for or wait for Black and/or Slack's videos. If you do your own film study you need to weigh things like the past opponents traits vs the future opponents traits, whether or not the fighter you're studying adjusts their gameplan based on opponent composition or sticks with a particular game plan. Even in dominating performances like McGregor vs Brimage and RDA vs Diaz you should still be able to pinpoint flaws.
RDA vs Diaz is particularly interesting. Diaz is a giant that lumbers around the octagon in that fight. At about the 3:38 mark of the 1st round Diaz steps in with his right jab, slips an RDA left hook leaving RDA very vulnerable but Diaz has shitty, shitty footwork and even though he kind of loaded up on his left he ended up throwing a confused uppercut that didn't connect because his right was half assedly holding RDA in a clinch to his chest. This resulted in Diaz putting himself in an awful position with both his arms tangled up and RDAs left free to fire. If Diaz lets go of the clinch as soon as he loads up he has a free power left hook or uppercut on RDA as he retreats but Diaz can't time it and leaves RDAs left free and clear to land a left hook.
As a thought experiment replace Diaz with McGregor in that equation. Conor's speed, timing and accuracy put RDA in big trouble there. Obviously this is just one exchange but the point I'm trying to make is that this fight is not even close to being as one sided as people think. I only provided the negative example of RDA because the question was "what swayed McGregor into making this fight?" The answer is that he legitimately thinks he can win.