Admiral Sims is actually a very interesting figure in United States naval history, but I believe those authors are giving him far too much credit.

Sims was sent to coordinate with the British Admiralty on the eve of the United States' entrance into World War One. His prior experience as an attache in diplomatic affairs was a large reason why he specifically was chosen. He was also an accused Anglophile, having been born in Canada, and the USN hoped his affinity of the British would allow him to have a better working relationship with his Royal Navy counterparts (although the Navy Department was sure to keep an unfairly wary eye on who he was actually working for). When Sims arrived and began his work, he was made aware of the reality of the U-Boat crisis and merchant shipping figures that were largely being held back from public knowledge.

Now, Sims was certainly a proponent of the convoy system, but that policy had already been in hot debate within Royal Navy leadership. When the loss of merchant tonnage reached a critical, and surely unsustainable, point, in April of 1917, the Royal Navy leadership began adopting convoys. Although Sims was certainly supportive of the system, the decision was organic within British naval and civil leadership. It stemmed from naval leaders like Alexander Duff and John Jellicoe (it took a lot of convincing and loss to turn his disapproval of convoy around), government officials like Maurice Hankey and bodies like the Ministry of Shipping (Lloyd George came under a lot of post-war controversy for giving himself a lion's share of the credit of enacting convoy, which most historians have struck down and nonsense).

Where Sims was important was in convincing the United States Navy to readjust strategy and assist in more efficient ways against U-Boats. Entering the war, the United States had an unrealistic strategy and unrealistic suggestions/expectations for fighting the war at sea. It was focused on keeping a large portion of its battle fleet near local waters in a defensive measure against U-Boats. Sims argued that submarines posed little threat that far out from German bases. Additionally, the growing mistrust of an upstart Japan, and the faint possibility of a resurgence in German surface raiding made the USN want to retain large portions of it's naval power. Instead, Sims repeatedly called for splitting the valuable escort destroyers from the main fleets, to be sent over the Atlantic and based out of Great Britain to assist in convoy efforts. It wasn't an easy struggle, but it was one that Sims achieved, at the end of August 1917 there were over 30 US destroyers based out of Britain from the 50 or so available. As well, Sims made clear that earlier American zeal to strike the submarines at their bases was unnecessarily risky.

Because of his constant urging, and criticism, of the Navy Department, Sims had a tumultuous relationship with the United States Navy 'higher ups'. Those tensions, simmering in wartime, exploded after the war ended when Sims brought charges of incompetence against the Navy Department before the Senate, who ruled in favor of the Navy. Despite the very public spat, Sims retired honorably and has had ships named after him.

Some sources:

A Naval History of World War One by Paul G. Halpern

Castles of Steel by Robert K. Massie

U.S. Battleship Operations in World War One by Jerry W. Jones