Wouldn't really say Solo MMR is an accurate representation of one's skill, since it's way too much dependant on the other 4 randoms in your team (solo queue was always horrible). Not to mention those 10 "calibration" matches are horseshit, and you basically get the same rating you had in unranked. That being said I started at around 3460 and dropped to around 3300 recently due to a loss streak.
When compared to other people (better and worse) I have on my steam and knowing their skill, I'd say it's an okay estimate though.