Maj-Gen Zabecki's credentials far exceed my own (non-existent) ones, so bear that in mind. That said, I feel he overstates the German case somewhat in the article. German victories in the Spring offensives generally happened where the Allied armies were weak. That is not a criticism of the German offensives, as it means they were well chosen locations, but it none-the-less speaks to a pattern.
Fifth Army was occupying a long portion of front, newly taken over from the French, on poor defensive terrain. The manpower shortage caused serious problems in creating the three layers of defense required by British military understanding of the time. Only the first layer was in place. This is a strong contributing factor to the German success in Michael as this meant that large numbers of troops were trapped and surrounded in isolatable pockets and there was no ability for counterattack. They were also assisted by the fog that morning, which is a hard thing to plan for. Once the front line was broken Fifth Army needed to retreat and block the Germans where possible without even the benefit of their compromised defenses. They were also not able to retreat along their lines of communication without risking losing contact with the French. In spite of this they maintained integrity and kept the retreat from turning to a rout, and in several instances inflicted local reversals and surprising delays on the Germans.
Georgette, meanwhile, took place in a sector covered by the Portuguese Expeditionary Force, a unit that had been abandoned by their government and was having serious problems with equipment, manpower and morale, and many of the surrounding units were those pulled from Fifth Army Sector to rest and recover. In spite of this Second Army was able to retreat along their lines of communication and German momentum was effectively stalled within a few days, though the battle continued for some time.
Blucher was launched against the area covered by the French Sixth Army, which at this point included British units recovering from Michael and American units still training. The commander in the area had refused, in spite of orders, to implement a defense in depth system, and maintained a single forward trench, that was again vulnerable to the extreme German artillery barrage and being cut off.
Often forgotten or lumped in with Michael was operation Mars, in between Michael and Georgette in timing. It was launched against the Northern end of the salient created by Michael, in Third Armies area near Arras. Here the British had a well built existing defensive system, as the front there had not moved in some time, clear lines of communication and supply and the advantage of terrain. The German attack utterly failed to take any of its initial objectives and was immediately abandoned.
The point I am getting at is that the Germans had great success in hitting the Allies where they were weaker and using that success to compel stronger fronts to pull back to avoid being flanked. Where the Allied defensive line was in place they had much less success. Therefore, simply shifting forces to more strategically valuable targets, though definitely a better strategy, is not likely to have the same level of success. In Second and First Army sectors, the troops would be well rested (without Michael forcing divisions to be cycled), and in strong defensive positions, able to retreat on their lines of supply if needed.
