We have a corporate website built on Wordpress and a web based product offering that our users log in to which is built on a different tech stack and hosted separately but all on the same domain.
Our marketing team decided to take the LOGIN/SIGN-IN link off the corporate pages on the home page as well as all other pages stating that the corporate website caters to corporate clients and they would get confused seeing a sign-in link on the website.
Our user base is obviously larger than our client base and hence my argument that we need to have a Sign-in link on the homepage and on all pages on the corporate website which is also what our users are told to go to in our marketing campaigns. Currently the Sign-in link is only on one page on the corporate website which talks about the product we offer and no where else. Getting to that page takes some scrolling and 3 clicks after someone lands on the home page.
But our marketing team is asking me for any metrics or data that says that users are confused doing the above actions to get to the Sign-in link. They believe that our users who need to reach the login page should bookmark the login URL if they need to get to it faster - but the product is offered to everyone on the web so I can't train them all so easily to do that.
How should I give them metrics they ask for? From where I stand, I feel this is a no-brainer that we need an always visible Sign-In link at the top of the home page but am I asking for too much?