^This. And people put waaaaay too much stock into over-night and Neilson numbers, which really don't mean much in 2015. After taking into acount Hulu, DVRs and other streaming sources, both AoS and AC are doing alright. Well enough, at least, to justify continuing on. I, myself, only have watched AC and AoS (or any other current show, for that matter) on Hulu.
One of my biggest problems with TV by the Numbers is their refusal to take anything other than overnight ratings into account.
Are overnights still the biggest indicator of a show's success and future renewal or cancellation? Yes. Are they the only factor? Not anymore.
And I didn't mean that AoS and AC are just commercials for Marvel, but that their ability to promote the Marvel brand bolsters their numbers.