Sorry but that's completely over the top, he hasn't come out and said he's a shit player. On the contrary, he has said he's a damn good player who just hasn't been at his best. He wants him to get back to his usual standard, just like everyone else on this forum. It is not an "attack" in any way shape of form.
Read what he said. He's basically having a go at a player because he doesn't fit into the mindset of the manager using tactics from the 1980s. Johnson is actually a very good modern fullback. If you put him back in time he'd look shite at rightback then.
Hodgson has a mindset. Fair enough. Can't change that (He's publically stated that he won't, in fact). But if your tactics include making class players look shite - don't blame the player. Look at your tactics.
Apart from anything else - given he's had a go at Johnson -if he does leave - and again - who could blame him? He'll have knocked millions off his price. And who will he replace him with? Yes. That's right. The Rightback version of Konchesky (Shudder).