Admiral King survived what you call mistakes because they were not considered mistakes, but were decisions on how to deal with a situation more involved then the people pointing out the losses during the 'second happy time' acknowledge.
An article discussing this can be seen here (emphasis mine).
In King's defense, noted naval historian Professor Robert W. Love has
stated that "Operation Drumbeat (or Paukenschlag) off the Atlantic
Coast in early 1942 succeeded largely because the U.S. Navy was
already committed to other tasks: transatlantic escort-of-convoy
operations, defending troop transports, and maintaining powerful,
forward-deployed Atlantic Fleet striking forces to prevent a breakout
of heavy German surface forces. Navy leaders, especially Admiral King,
were unwilling to risk troop shipping to provide escorts for coastal
merchant shipping. Unscheduled, emergency deployments of Army units
also created disruptions to navy plans, as did other occasional
unexpected tasks. Contrary to the traditional historiography, neither
Admiral King's unproven yet widely alleged Anglophobia, an equally
undocumented navy reluctance to accept British advice, nor a
preference for another strategy caused the delay in the inauguration
of costal escort-of-convoy operations. The delay was due to a shortage
of escorts, and that resulted from understandably conflicting
priorities, a state of affairs that dictated all Allied strategy until
We might even speculate that that shortage of escorts was due in part to the Destroyers for bases deal, which in late 1940 placed 50 US destroyers into UK hands:
The destroyers-for-bases deal was an agreement between the United
States and the United Kingdom on September 2, 1940, according to which
50 Caldwell, Wickes, and Clemson class US Navy destroyers were
transferred to the Royal Navy from the US Navy in exchange for land
rights on British possessions.
So the US was short of adequate vessels to perform two critical tasks at the same time-protect troop transports heading to England, or protect merchant transports along the US coast. King chose the military option, protecting the troop transports allowing US troops to enter the European Theatre. You can't fight a war if you cant get there. This would be looked at as a tough decision, but King chose protecting the troops over protecting the merchant vessels. Perhaps if we had those 50 destroyers he could have done both. But the first happy time might not have ended without them, so the statistics on these 'happy times' might be quite different.