Assuming you treat Howard to Lebron as an equal, which I wouldn't (but in a head to head battle league, with playoffs, and two C spots, could be argued)....
McGee = Noah, with a slight advantage to McGee as Wall is starting to beast, and Blatche looks like he's spiraling.
Jennings = Rubio, with a slight advantage to Rubio, as Jennings may not keep up his production at quite this pace.
Marcus Thorton = Richardson, with an advantage to Thorton at this point in their careers, however, and the emergence of Reddick for the Magic.
Which has me looking at this like Andrew Bynum, 2nd best center in the league, for Jarrett Jack.
And if I had to bet on the other match ups where one side outperforms the other in a significant way...I'd have to say it'd be Lebron, McGee, and Thorton, IMHO.