In one game I found that removing the air forces did make a large difference in the outcome, but it was much less in others. Some so much less the air components seemed there more as 'chrome' or trimming than any important part of the game. I cant say which game model is correct. It seems to me the game designers were shooting from the hip in some cases, or fishing for a result in other cases. I've not yet found a usefuly detailed account of the bomber sorties made by the German AF vs the various areas, or is support of which corps or armies. The accounts I've seen suggest more were used vs one are or another, but its very difficult to judge the exact difference. ie: If anyone has information on the number of bomber sorties flown against the Fr 1st Army area on the 16-18 May, or the 9th Army sector on the 13-15 May it would be helpful. Knowing only that 4000 or however any sorties were flown total in X number of days does not really help to understand why one French group held together & another failed.
The German 'decision making' is not so much the question as is the French. The slow Fr stratigic & operational decision/execution is most marked at the top in the campaign, at the player level This makes it difficult to model & I've never seen any games that clearly mastered the problem of reproducing the handicap that existed at the level of Georges. The designers tend to focus on a few German tactical strengths & ignore other strengths or weaknesses on each side. ie: The French artillery was more concentrated at the tactical & operational level than the German. Where the commanders used it correctly this concentration, and a possible advantage in speed of action frequently suprised the Germans. ie: The action reports from the officers of the 3rd & 4th Pz Div have a lot of hyperboyle over the effects of the French artillery. One described the French artillery concentrations as worse than he had seen in WWI. In the engagements around the Belgian villages of Wasain & Thisenes the German reports seem as if the Germans were opposed by ten or fifteen battalions of field artillery. In reality the French only had five, four of which were light 75mm guns.
Its this sort of crude modeling that makes the games of my experience suspect vehicles for studying alternate decisions/stratigies in this campaign. By comparison games modeling the Brit/US/German campaigns in NW Europe or the eastern front function a lot better. That is you can closer to historical results without resorting to critical special rules.