Sloppy play isn't really on the IGL though, they can't micromanage their roleplayers' every move.
That being said, poor leadership or a bad game plan will generally affect roleplayers more than stars. This is most obvious in stats, because if they're not supposed to be in positions to frag out even when things go well, then a bad team performance is gonna tank their stats. Poor in game leading will also affect a roleplayers understanding of how their role should even be done. The point of even having roleplayers is to do specific tasks that are necessary to win, but don't necessarily involve getting frags, but if there is no plan (or a plan that isn't very cohesive) for what you should be doing in a round then they're going to look lost.
I think this is where Rush is at rn tbh. I think it's pretty obvious to a lot of people that the team has a structural problem. The parts are there to be taking wins against really good teams, but for some reason it's not clicking, and I don't think you can put that squarely on Rush. He's been a very good support at times, and I believe that teams degrade much faster than players, so he can very likely still do a good job. I think the next step is to bring in a better IGL or coach, and of the available options MSL and zews are probably the best options.