None of those cards you mentioned are considered top tier performance cards. Which is what my point was. It would be nice to have a Titan in a MBP though. I'm looking forward to Maxwell as well.
Im not saying changing but surely they have kept themselves in the mainstream area. There is such a gap in performance of higher end parts, that to consider this 650m anything else from mainstream is absurd.
So the point is apple = mainstream performance, nothing more nothing less
Of course none of the GPUs are considered top of their tier. However they have been getting higher and higher on the list. For example, on Notebookcheck.net, the latest GPUs used by Apple have been in the bottom half of Class 1, whereas previously they have been distinctly Class 2. No doubt hastened by the creation of BootCamp, Apple are no longer designing MBPs to play Mac games, but any Windows game too.
And the 6750M-6770M and 650M-660M are not Mainstream, nor are they mid-range. They are Performance cards, that can play any computer game at reasonable settings. What they are not are Enthusiast level cards, like the 7950M or 680M.