BRM is important to avoid to go broke, so you (dramatically) increase this risk if you don't use it... i was and am aware that at the moment where i had my 2 BI, i could have gone all-in preflop, get a huge suckout by someone holding 2 7 and then i am done...
it didn't happen, that is kinda luck :-)
and i don't trust my 'A-game' so far... i had upswings before and seems kind of easy to go up, but if you get greedy and you are not patient enough the way down is even faster :-)
i hope i changed my game (feels like it^^) but i can tell you in 2 or 3 months whether the way just went up (in the long term) ;-)
it is easy to say: i played my a-game when it goes up and blame it on the downswing if it is not running so well...