What does a "commander-command tour" mean?
“The new CO is Commander Bill Hughes,” he said. “He’s a classmate.”
That spoke volumes: the Captain was completing his commander-command tour, promoting to four stripes, and on his way to an even bigger ship. His classmate was obviously a little bit behind the career power curve.

Question

What does a "commander-command tour" mean?
“The new CO is Commander Bill Hughes,” he said. “He’s a classmate.” 
That spoke volumes: the Captain was completing his commander-command tour, promoting to four stripes, and on his way to an even bigger ship. His classmate was obviously a little bit behind the career power curve.

Answer

A "command tour" is a one-or-two assignment when you act as the commander of a ship.
1. Some ships are allowed to have a commander-rank officer as the "captain" of the ship.
2. Other ships must have a captain-rank officer as the "captain" of the ship.

A commander-command tour is #1.  He served as the captain of a boat even though his rank was lower than a real captain rank.

Answer

It seems his rank is higher than that of the commander.
Because of promoting to four strips.
We either say commander or commander in chief. C-i-C