If the price was right, I'd trade him.
Ditto the other Johnson that's been mentioned in this thread, PJ.
However, PJ's worth to us, as a tall player, is likely going to be more than what CJ's is to us, as a HBF'er.
Fwiw, 25-27 is hardly 'his' gap - he's 22 (if you know that, I'm not sure why you brought it up in the first place).
edit: did you mean this gap, referring to the 25-27 year olds? That'd make sense, but trading in a 27 year old isn't the way to go.
It's better than the threads that suggest we can trade rubbish to get first and second round picks...