As always: definition is important, in this case of the term masculine. 

Submissive men are not your typical alpha males, obviously. But only in that sense they may be considered ‘less masculine’.

The sexual prowess of submissive men I would rate as : probably way above average (I include the word probably because my sample is statistically not large enough).

Obviously, I don’t view submissive men as less than dominant men – on the contrary. Readiness to serve women I consider a masculine trait. 

What about their physical appearance? Here you’ll find no ‘standard type’: submissive men range from short to tall, athletic to leptosome etc.

So there is an answer to your question. But as I said: it depends on what sort of ‘masculinity’ one is looking for. When I make him wear a typically feminine garment or turn him helpless by tying him up, I don’t see him as less masculine.

It’s OK if not everyone understands.

Source: Boss Ms Becky