I'm not sure where this notion that Johnson is useless and washed up is coming from. Even if he loses a step, he's still faster than Adams and Cobb and superior in every other way imaginable. Especially since Adams will surely be demanding close to $10M on the free market soon, I'd take Johnson in the Twilight of his career rather than a guy with a ceiling as a solid #2 over the next few years.
Calvin Johnson during his career was incredible - I think most people would feel comfortable ranking him on their top 10 all time WR lists. His career also ended somewhat prematurely, and not due to injury per se, meaning he could very well still have some good bit of high octane gas in the tank. Even given this, bringing him onto the team for a 1 year deal would be a mistake, both for this year and for the future, for several reasons.
1) He hasn't had any game time in long enough that, at this stage, he would likely not be fully back into football form till a quarter or third of the way through the season.
2) Our offense is highly predicated upon timing and route running, and getting that sort of thing down
in tandem with your QB takes time, and likely he wouldn't be fully versed till halfway through the season.
3) Bringing him in would mean dropping one of our bubble guys, and that means sacrificing a promising prospect of future production (for most of our bubble guys are promising prospects) for at best compromised production for part of this year.
4) Given the first two points, his role on the offense would be described as "hope that he is still physically talented enough to be get separation when Rodgers scrambles and routes break down," which is putting yourself in a position to only have success on plays that fail. If you consider that between 25-33% of called passing plays will probably have some element of this in them, and you agree with my above generalizations, then you figure that you are dropping a prospect and paying a guy a good chunk of cash to come in for between 8-12 games of being able to contribute maybe 1/4 to 1/3 of the time.
Granted, if he stays healthy and things go well, by the time playoffs come around he's probably getting more fully meshed into the scheme and has at least a bit of rapport built up with Rodgers and is getting perhaps some designed usage from MM, but that is hypothetical. All coaches talk about how important it is to have a full offseason to work with your team-mates. There is an equally likely chance that CJ is around just to be there for the occasional hail mary.
