That is not expected, but could explain a lot if true. Also the comment about the captain seeing the need for power first does create a bit of "conflict" in the pedal stroke.

One other factor, as is single bikes, is the quality of the components such as wheels, bearings, weight, etc. Getting a tandem of a quality equal to one's road bike might be beyond one's budget as in my case, so a heavier bike with lower quality components carries it's own penalty.

My wife is currently a D rider due to injuries. When she was a C+ rider we could handle a 40 mi B ride with power to spare. Now we would struggle.

When we first started she would complain if the cadence was much above 75. "Too fast" she would yell. As I worked on her pedal stroke (She was a masher) and got her to pedal in circles, her cadence went up. We can now hold 85 rpm no problem. She still get' a bit antsy above 95 for any lenght of time.