He's not just a great counterstriker...hes almost only a counter striker. He can't throw in combination very well, when guys close the distance he's quite hittable (doesn't move his head or feet well), gest flustered and tends to rely on clinching and grappling to defuse it. His great defense and strike accuracy is reliant a lot on having such a low output and forcing his opponents to always act first when they're already timid over the threat of being taken down.
Vs Volk in particular who by the way has had reach listed at 64in, 66in, 69in, 70in, 71in and 71.5in over the years (kinda doubt his reach is actually longer than Islams). Volk looked much shorter and not long, he couldn't get the jab going and had to forego it altogether relying on leaping and blitzing himself into range due to the height and length disadvantage which played right into Islam's striking style and physical advantages. Islam isn't pillow fisted by any means but he isn't a big hitter, being naturally a 10-20lb bigger man really helps make you seem like you hit hard vs Alex who isn't a particular hitter to begin with.
I've seen nothing from Islam's striking to make me think he's going to outclass Dariush standing who's also a southpaw, every bit as fast and hits and kicks a lot harder. Beneil is chinny though and can get wild but I think he can be a serious handful for Islam. Same for Fiziev if he can stop some takedowns, Islam won't have a ton for him standing. A guy like Jalin with his length and power will force Islam to spam takedowns, even Damir or Guram are clearly better strikers. It's Islam's complete game that makes it look so strong.