Rommel was outnumbered massively in north Africa theatre, and he only commanded 1 division in battle of france.
In the first instance, if he was massively outnumbered why did he risk the lives under his command on foolhardy attempts to capture the entirety of North Africa against a numerically superior enemy? Part of being a military commander is to look after the men's lives under your command ... they are afterall the ones who will do the fighting.Then, when we look at the two major offensives that Rommel undertook in North Africa.
The first major German success following deployment of German forces to North Africa ('Sonnenblume'), was the reconquest of Lybia and pushing the British back through Egypt. This occurred on the back of the best equipped British units from XIII corps being sent to Greece. At this point, Rommel had the best part of 7 divisions (2 German and 5 Italian), strong air-forces and the benefit of having essentially new equipment. Compared to the British situation who had 1 Division and 3 independent Brigades (i.e. missing Divisional support elements) - not only were they massively
outnumbered but the 3rd armoured brigade had few tanks (and those they had were literally falling to pieces due to lack of spare parts) and the 7th Armoured division was unable to reequip (having been left in North Africa as one of the worse equipped units). The operational reserve was a motor brigade with no artillery or anti-tank guns. The German forces were free to outmanouver and outflank the British who had limited opportunity to counter-attack and harry the advancing force. In summary, Rommel had significant numerical and equipment superiority which enabled him to keep preventing the British from re-grouping and setting a defensive line.
As for the second major success, the Axis forces were only lightly outnumbered. However, what has to be considered there is that most of the British forces were relatively new - poorly equiped and inexperienced. Late in 1941 the Allies (well, Britain and the commonwealth) were also fighting in Syria and Persia - the Veteran Australian 6th 7th and 9th Divisions were supposed to be available to Middle-East command (according to Brooke's diaries, one of the reasons the British pushed to such a forward position), but were subsequently sent to the Eastern theatre instead. Fortunately, for Rommel, this left a thinly spread, tenuously supplied force ready to be attacked. Far from being a master-stroke of Rommel's, it was more a matter of poor strategic planning and over-confidence on the British.
So, no, Rommel wasn't massively outnumbered. In most cases, he had local superiority and was aided by the fact that the British had to keep moving forces around the world to firefight strategic setbacks.