Why is my m-dot site outranking my main site in SERPs?

[Etna]

My client has a WP site and a Duda mobile site that we inherited.

For some reason their m-dot site is ranking on P1 of Google for their top KWs instead of the main site which is much more robust. The main site might rank beyond page 5 when the generic home page for their m-dot site appears on P1.

Does anyone have any idea why this might be happening?

[Etna]

Sorry for the cliffhanger, but I did some more research and wanted to follow up.

After looking over the mobile site's backlink profile, I'm convinced it's not related to the mobile version having a better backlink set than the desktop (mobile backlinks = 4, desktop = 1,400). The overall quality of the backlink profile on the desktop version does not send up any red flags for me (or any of the software used to analyze). Mostly industry related Q&A links, local business listings, fairly low on general directories (about 3%), other hospital links (client is in the healthcare industry) No manual penalties were ever issued to the desktop version.

I appreciate your feedback as well Bridget, the rel=alternate & rel=canonical for each version of the site appear to be appropriately inserted based on Google's guidelines, so I'm still scratching my head trying to figure this one out.

[Etna]

Thanks Spencer,

It's hard to be specifically vague

I will check into each and re-visit this question so give some more detail on what's linking under the hood.

[spencerhjustice]

Assuming that each site is optimized similarly I would assume that either the m. version has a better linking profile or more likely that the desktop version has spammy links and is suffering from an algorithmic penalty due to penguin. I would look into that first. Check webmaster tools under search traffic > manual actions to see if there's anything there as well.

Like the majority of questions in these forums its difficult to give a more specific answer without being able to look at the actual sites in question.