I'm not talking about how many men Germany had overall, I'm talking about how many men they had at the decisive point and how much territory they had to cover. IOTL it was at the Marne and ITTL we haven't seen it yet. At the Marne IOTL the Germans had some 3 Corps masking Antwerp and 2.5 Corps besieging Namur which were sent East once Namur fell which in total equates to a full Army that was crossed the border but wasn't at the Marne. In detail this means that for example regimental machine gun companies that started with 8 MGs were down to 4 or 5 MGs by the Marne. In contrast the BEF for example withdrew onto its 5th and then 6th infantry divisions, and after the Aisne the entire BEF used the coastal railway to move to Flanders because there were no German forces in the area to stop them.Riain sorry the Germans had 2.1 mio men against France with France having 1.5 and 0.2 BEF. OTL Germany moved one army east, and needed one to deal with the Belgiums.
ITTL Joffre has moved two armies into Paris proper so the Germans still have 2.1 mio men and the French in armies that count 0.9. if you have something around 40% of the army strength of your enemy achieving local superiority is pretty hard.
And with Paris encircled it is a matter of weeks at best before the French armies run out of ammo.
ITTL 1st Army will have to cover a line from Paris to the sea, a distance of 160-200km, while the other 2 armies besiege Paris and the other 4 armies will have to cover the 500km from Paris to the Swiss border. That's a LOT of space to cover, particularly for 1st Army, and the BEF may be able to put all 6 of it's divisions against an area of front held by 2 German divisions between say Dieppe and Paris.