Body fat levels and gains on cycle

I've read on various forms people stating that when all things are equal the leaner guy will make better gains. something to do with increase hormone receptor sensitivity and higher free test. I always chalked it up as broscience. This blast i'm doing now it seems like making far better gains than ever before and everything is the same except i started this time 30 pounds leaner than any previous blast. what do you guys think any truth to this claim?

There is a good thread by Marcus that discusses "priming" in depth and if practiced it works well and makes great sense. The idea of cycling at a low bf % is important also in terms of having an easier time managing sides and not having to worry so much about putting on some bad weight via a bulk where as if you are at a higher bf and bulk now you have even more flub to drop and you increase your chances of having sides.