It doesn't feel like so long ago that Stone Cold was on tough enough telling the final three contestants about how successful Miz had been, making his steady rise to the top and becoming the champ. Oh how things change... If you look on the WWE website, they always refer to him as "the former United States champion" instead of WWE champion. They do a similar thing on his profile, where they've put his record as a WWE champion at the bottom of the list of achievements, but on every one elses that achievement is at the top. Seems like they're going really out of their way to bury the Miz.
Anyway, I think that the Miz did a good job of giving Alex Riley the rub, but that's because he was relevant back then. He's lost to a few guys like Kofi and Brodus, but did it really mean anything? I like the Miz, I just think that he should've stayed in the US title picture, he was an awesome mid-carder. Sometimes it's better to stay in the mid-card as a respected and legitimate competitor, rather then attempt to goto the main event and flounder. Truth be told, Miz was only at the top because they couldn't find anyone better at the top. I thought that he looked like he'd be alright at first, but things got ugly pretty quickly.
So to answer your question - no, Miz probably couldn't put anyone over at the moment. Even as a former champ, he just doesn't mean alot anymore, and that's reflective of the way that he's treated by the brass.