Well, if we're still comparing gla1ve and blameF, just take 2020 as an example. Not only does blameF have a MUCH higher impact rating, he also has much, MUCH higher number of wins in any clutch scenario.. so I have absolutely no idea what you're talking about. blameF is essentially great at clutching.
2018 gla1ve was crazy though, especially when it comes to clutches. He would win almost double the amount of 1v1s than he would lose.. which is just ridiculously high on that level for an IGL.