Do you agree that sales effectiveness comes from the selling skills, product knowledge, and competition knowledge?

Yes I agree but the product should be customer value driven as it is the key unique selling and value proposition.

Yess i do agree with your point of view we need all the skills like product knowledge, customer service, competitors knowledge, aftersales service, neworkmarketing skills, merchandising skills, an more important customer satisfiction in all the ways to improve the sales of any product.

The mentioned are qualities of good salespeople. in addition to these qualities, Sales effectiveness requires planning, segmentation, targeting, etc.

In my opinion the sales effectiveness can be achieved by selecting the right people to deliver the right message for the right customers at the right frequency with full integration between Marketing and sales.

Yeas i agree.