Was I unlucky or outplayed in Afrika Korps?
Both actually. 


You were unlucky to not roll for a supply in time to avoid supply death;
but the first supply to arrive was only keeping you alive, not allowing you to  use the greater mobility of AK to effect. 
I have never seen, and have difficulty imagining, a situation where a "token force" in Tobruk would have prevented you from using one or two 2-2-4's to restrict the Brit from bottling you up.
Even if you rolled supply at better than the expected rate, I suspect the loss of time you suffered from this escapade was sufficient for the Brits to land their November '41 reinforcements and wall up Alexandria.


Great game - I played it extensively in High school, and occasionally in the many years since. Have you checked the archive of The General for the many fine articles on this game and its strategy and tactics? The General Archive

Update:

The key advantage that the Axis have early in the game is speed. A successful Axis player must use this to compress the British maneuverability early on to ensure a win. Allowing yourself to be bottled up in Tobruk is an anti- pattern for the Axis player, regardless of the importance of Tobruk.