Well Yair has demonic kicks, it will always be a trouble for everybody in that division, he sets them up pretty well.
As much as Yair is the flavor of the month : He relies too much on kicks to finish his fights. His boxing is subpar. Decent, could stop fights with it, but yeah, there are better hands at FW.
Against Bruce Leeroy he relied too much in closing distance and striking him, and as i said, his boxing isn't his main KO weapon. Bruce is a lanky dude, hard to close distance and land a good one on him. pretty sure BJ wouldn't KO him either.
Now, one thing he exploited perfectly : the tendency that BJ, much like a shitload of old schoolers have, to keep their head static at centerline after striking. And when you're older, you're much slower, so you're even more static.
Front kicks are the best weapon to capitalize on it, you can throw it from a good distance, if you hit the ball of the foot right at the chin, nobody is going to survive that. If it catches them by surprise is almost 100% KO chance. Anybody giving Yair space enough to be creative with his kicks, will suffer.