He crucifix mounted Faber for christ sake and had him completly helpless and stuck, look at who Aldo have been facing and it's really not the hard to see why he hasn't been primarily going for subs when he's had people on the ground, it's not easy at all to lock up subs in MMA and you also risk losing position by going for them ESPECIALLY if you are in top position.
In fact if you are in top position in MMA there really isn't any point what so ever to start fishing for subs when the success rate of you controlling your opponent with strikes is much greater then a sub alternative. The one exception would be if you manage to get someones back and have them flattened out in that case a finish by strikes and a RNC would have about the same finishing percentage.
Conor is a 'brownbelt' under John Kavanagh (which means fk all in reality) in competition he wouldn't even make it out of a bluebelt bracket. The best grappler at that garage gym he trains out of is Gunnar Nelson, and Gunnar Nelson's accolades as a blackbelt in competition reads like a big fat ZERO, infact he's failed to even place or get out of the initial stages since becoming a blackbelt (this due to competition level between brown and BLACK being ENORMOUS it's basicly the difference between you facing Jonny Brownbelt and the likes of Kieran,Cobrinha,Terra,Mendes,Garcia and so on)
Aldo is a multiple brazilian national champ/mundials & pro's winner. He also has submission victories (yes plural) over Rubens Charles.