Taller than Lee Evans, desperate for playoffs, catches everything. If you could get 3 1000 yard seasons out of a tall, productive 2nd rounder and then were to never hear from him again, I would still take it. Think about who he replaces, and what he allows other receivers on this roster to do and be.
He would be an instant upgrade and would have zero of the learning curve of a rookie. Draft picks are assets, but they aren't gold. Johnson is money in the bank, and talented possession receivers can have long careers.