Didn't the Patriots sign Chad Johnson last year? How did that work out? The Patriots organization does make mistakes too. Regardless, they are simply working him out to see what he has to offer. We will wait to see if he signs.
Edit: Sorry, misread your post. Seems we may agree.
In regards to the catch rate statistic, that is just one statistic when rating receivers. It is not the be all end all. The point about him being a downfield receiver and therefore having a lower catch rate is valid. The point is that he is 35 years old now and he is no longer an efficient receiver in that role. You can go to that website I initially linked and view his other stats, they are below average for an NFL receiver.
Rey made a good point about him being a red zone target for us. We have AJ for that and we rarely do throw the fade to him. I would like to see that change. Who is going to defend the decision to toss it up to Plax with AJ on the field? Especially when it doesn't work.
If we lose AJ and Plax is still available, then I would consider it. Until then, it is a waste IMO.