Coincidentally, I was playing Rengar jungle during the game I'm using these examples from. The Yasuo was ganked really early on. Like, Level 3-4 early. The enemy jungler was a Lee Sin, so I understand that he was going to be an early aggressor. the problem, however, was that the Yasuo either wasn't aware of that possible (er...more than likely) early aggression from the Lee Sin OR he knew about it and just didn't care to prepare/look out for it.
With that being said, I was Rengar, so there isn't much I can do, being level 4-5ish. Now, I know it isn't completely impossible for Rengar to gank pre-6, but ganking for Yasuo was completely out of my reach, due to him being against a Karma whom he had (or thought he had) literally sitting under her tower. Even if I wanted to help him, I wasn't level 6 yet so the only way for me to gank for him would be to literally expose myself to Karma and, in a sense, taunt her with my presence. Problem with that is, it wouldn't do much given that Lee Sin could come in and he, along with Karma could easily kill us both (if not just me, and Yasuo escaping with a sliver of HP due to his shield) Either way, the end result didn't seem to be in my favor so I ignored it and tried to help the others.
By the time I hit Level 6, Lee Sin had already killed Yasuo 3 times, so counter ganking with my ult was impossible because Yasuo was already to far gone to assist against a fed Lee Sin. Believe me, I wanted to help him. But my desire to help him wasn't so that I could help him. I simply desired to help him, so that the rest of us wouldn't have to continue suffering for him feeding Lee Sin by not playing passively (hell, even just a tad bit less aggressive). But, again, the situation was just too far gone.