One quick modification I've decided to try is taking only low-TOI NHL forwards to set a baseline standard to get a best fit line, and compare all my 600+ 5-on-5 mins forwards with that line, rather than an all-encompassing line which will be skewed by good and bad players alike.
I guess here you have a list of some of the best seasons since 2007-2008 in terms of Corsi. This looks a bit better. I like that more of these guys are in the black this time. The lowest positive player is Ilya Kovalchuk (around #600), which makes plenty of sense. There still are good players at the bottom, like Chris Drury and Jarome Iginla. I guess when it comes to playing defense they don't attack all that much or try to, say, keep chances from the outside. Some other tough minutes forwards like Frans Nielsen, Jordan and Eric Staal, and Zach Parise, though, show up near the top.
Next time, I hope to have done player averages and incorporated zone starts as well. For right now, guys like Martin St. Louis who Behind the Net lists with spaces in their names are giving me some trouble :(