I remember the days when Rookies were drafted with the idea that they would not play in their first season or two. They were expected to learn the system and learn how to be Pros. Times have certainly changed.
Johnson may or may not turn out to be a good player for us but at this point, it's way to early to make a decision on that. Anybody who thinks it's wise to do so should look back at Carter or Romo or a Laundry List of others who did not play significantly in their first year in the NFL.
Tom Brady, possibly the best QB in the last 15 years, certainly amoung the top 10 QBs who have every played this game did not play in his 1st year in the NFL. Three passes the entire season I believe. I wonder where New England would be now if they had decided that Brady was not worth waiting for.
Roger Staubach, arguably the greatest player in the History of this Franchise did not play in his 1st year. Heck, he didn't play in his first 3 years, after being drafted and then, he barely played in his first two years with the team. What would have happened had we not waited for him?
Time will tell on Johnson but the wisest course of action, at this point, is to be patient with him and see what he develops into.