The majority of the 'older' or more experienced MPs are from SK, AB and BC.
It was a matter of geographic representation and not wanting to have a Western Canada heavy cabinet.
There are a good five or six MPs from Alberta alone who arguable have the experience to serve in cabinet but aren't full ministers at the moment. (Ablonczy, Hawn, Jaffer, Kenney, Rajotte.)
Could you imagine the howls from central Canada with eight? nine? ten? Albertans in cabinet?