In the Battle of the Sector 001, when Picard came to Earth to engage Borg after violating his direct order, he had a special coordinate in mind which could blowout the Borg cube and Starfleet had no idea about it.
Then, there's this thing called luck which rolled in the favor of Mankind and Riker was seen saying, "Admiral's ship's been destroyed." After that, Picard wasted no time to broadcast "I am taking command of the fleet." and gave everyone a special coordinate to fire. And, everything went smoothly and quickly. No conflict. No discussion. No thought of conspiracy from Picard (there was a reason why Picard was given orders to stay out of it). How can this happen?
What does protocol say? I don't think Picard was just below the rank of Admiral. Why didn't other seniors object? Specially, when Picard wasn't fit for fighting against the Borg (in the eyes of Starfleet). And, why did everyone follow Picard's order?
Here’s the Battle of Sector 001 in case you have forgotten: