You just removed little bit of movement speed from his Q. What he needs is nerf on his cooldowns and (true) damage output. How does a guy, who builds flat tank, be able to take down enemies with Q, E, R combo in couple of seconds.
2000+ true damage ultimate on tanks, 1000+ on squishies.
During laning phase, he gains free 30 armour and magic resistance -> tanky as F.
Want to trade with him? -> He silences, clicks spin and you couldn't retaliate at all, have to flee instead. Leblanc had her silence removed because trades with silence was "unhealthy". Why then is Garen allowed to have such mechanics?
Seriously sick of how broken the juggernauts are... Darius got a nerf on damage and heals, Garen too now please.