Oh christ, please never ever mention Marvel's "official," stats (unless you think Sabretooth is really as strong as Rogue w/Warbird's power).
Even if Emma is stronger then Cage (class 50 would put her at half of Colossus's strength, and that's just bull), she doesn't have the experience or intuition of a hand to hand fighter.
Not that Emma's totally untrained, but aside from the mandatory self-defence all X-Men have to know, why would she even bother? Between her telepathy and diamond skin, what would give her the inclination or incentive to train to become an expert melee combatant?
This is just one of the reasons I can't stand characters like Psylocke. She's psychic.... but a martial arts experts..... wtf? Why is this grossly overpowered character even on a team?
The point is, Emma has some training, but how often do you see her get into melee combat? She hasn't had her diamond skin very long, and her psychic abilites are more useful on a team with Wolverine and Colossus for frontliners. Hand to hand is Cage's bread and butter, it's how he does what he does. This is like putting someone who's had years of martial arts training but never been in a real fight (or only a few) up against someone who fights in tournaments and matches all the time.
Cage pounds Emma until she's dazed, then he buries her up to her neck and leaves her to get picked at by gulls. Cage 9/10.