Lets say that the Brusilov offensive is a Russian disaster. The forces were about the same (Russian 54 divisions vs 49 on the AH side). The key of the victory was Brusilov's use of infiltration tactics, a powerful but short artillery barrage, and in the select infiltration areas moving forces 75 - 100 yards from the AH line.
I have read that the AH had created an excellent response system that after a barrage was lifting they had xxx amount of time to get from the shelters to the trenchest. In this case the AH never had the opportunity to get to the trenches but were caught while deploying.
In addition Conrad had asked Falkenhayn to replace AH divisions with German divisions so he could transfer troops to attack Italy at the B of Asiago. Falkenhayn refused so Conrad pulled some of his best troops from the eastern front to support the battle of Asiago. Leading to the breakthrough of Brusilov.
SO TL
1. Conrad plans the redeployment of some of his best units and 2000 HA to the Italian front. The AH leadership is concerned with the German refusal to move troops to the eastern front to support the AH withdrawal, and replaces Conrad with Satuffenberg (Arz).
2. Several deserters from Russian army talk about the pending offensive and the forward positions they are preparing.
3.Air recon confirms the deserters stories.
4. Arz withdraws the selected troops that were targeted to go to the Italian offensive, to rearward positions 15 miles back. Arz also alerts the Germans to the pending offensive. German recon confirm the situation, and shift 5 divisions south (they had to shift 16 divisions to help stop the offensive in real time)
5. Brusilov offensive starts and the first line is over run, being lightly held by the AH.
6. The AH troops move forward to the 2nd line and dig in 3rd, 4th, and 5th lines. The Russians are caught advancing between lines by the AH troops in crossfires and no man lands. German and AH forces cause 1 mm Russian caus (real world) but lose only 200,000 (vs 1 mm).
7 The counter attack drives forward with the Russian front collapsing in June / July 16. The collapse spreads across the front.
SO questions :
1. Impact on the Russians throwing in the towel -- Having AH is an effective combatant for the rest of the war vs a crippled force. ( i would guess Russia out of war after the Feb rev in 17 or before)