The guy isn't a draw though, he can be a bad draw when you look at his individual segments, they usually show a decline in viewership but are usually propped back up by Cena/The Rock/Undertaker/insert person of relevance and ability to draw. Drawing is just as much about drawing on viewers on Raw as much as it is about getting people to buy pay-per-views, I'd imagine if he was drawing ratings with his work on Raw then he would of headlined more shows but he didn't.
But there are probably lots of segments which didn't draw, post-Wrestlemania tends to be a bad time ratings wise for WWE. Besides the AJ/Punk/Bryan triagle storyline was deemed a sucess and drew some solid ratings, and a number of ppvs where Punk has headlined or at least been in one of the top matches have done quite well, MITB 2011 and NWO 2012 being examples. As someone else pointed he did out draw Cena in terms of merchindise, and gets a consistant response from the crowd. For me he is a draw, how big a draw is up for debate, but WWE would be worse off without him.