Street fight where there is a clear size and weight difference, yes.
I mean, unless someone is having a coronary during the exchange, conditioning means little. Conditioning only really matters if we're talking about extended fights, which tends to happen more in competition than in street brawls.
What tends to happen in street fighting is people square off, they clinch, and they wrestle around. In those phases someone can get knocked out when they square off. The can get slammed to the pavement when they clinch. They can get taken down and grounded and pounded when they wrestle around, and everything in between. Those tend to be the phases of documented street fights, and they tend to be relatively quick affairs.
The relevant point here is that we never see a small Aikidoka tossing around a larger assailant. We don't see it in competition. We don't see it in exhibitions. We don't see it in street fights.