Hecarim in Dominion - is he really THAT bad?

I regularly see the Dominion tier lists rating Hecarim fairly low (although post-buffs I think he might have been promoted but I'm not entirely sure), but I'm curious as to why. I'm sitting around 1400-1500 MMR and he's ended up being my go-to pick into a lot of solo and duo comps that are often AP heavy and lacking in appropriate beef, and I usually am able to put out really strong performances in terms of map coverage, frontline tankiness, and even damage, which is surprisingly quite respectable. I've seen wolferer run him to great effect and I've taken some tips for play and incorporated them into my own game so I'm curious, what about him keeps him from excelling at the high level unless wolferer is using him?

Also, I often actually run him top. With his high mobility through his E I find I'm able to provide a lot of map coverage and engage on fights or make ganks on bot with impunity. I build Triforce first and I tend to go into tank items, maybe adding a few pen items or a Hydra if I need a bit more offense. I've also been running early Furor boots on him which gives him a nice degree of stickiness and an offensive boost. I've found he's quite durable and with the right defensive itemization can really ruin a lot of people's days. So what's his issue?