Grumpjaw's perk makes him naturally tanky, allowing him to cs without fear early on when he builds book or even when he doesn't. An A+B combo early on easily wins you early game all ins delaying your opposing laners trade. Late game you provide plenty of utility if you get pulseweave and crucible

Warhawk and skaarf should be S-tier for mid imo they are so oppressive in lane, warhawk's passive allows him to completely outrade every other midlaner due to it's massive range and relatively high damage. And with skaarf's recent A buff your average t10 player will land 80% of their A and get free damage on you. But overall your midlane tier list is decent. The biggest problem I have would be your top tier list. Currently in t10 Joule, blackfeather and Leo are the highest priority picks...