As a guy who has shopped Target clearances for probably coming up on 15 years now, I can tell you, they ain't what they used to be.
Now, maybe it is just a cyclical thing but I suspect not, and that Target has gotten more sophisticated in their inventory control practices...and it is not just video games, but a lot of other areas too from what I have seen.
They just simply don't seem like they have as much left over crap they need to clearance like they did 4-5 years ago.
I honestly can't remember the last decent wide-spread VG clearance at my local Targets (and I have 3 that I regularly hit) where it used to be a monthly event it seems.
It is VERY simple. Target sort of finally got the hint about 3 years ago that people would wait for stuff to go clearance because Target would over buy on what they would sell to you and i. As a result, they dramatically cut back on how many video games they would send to all stores, even guaranteed sellers. About the only games they will go nuts and buy in droves for consumers would be the usual culprit such as COD, GOW, etc. You will never again see the insane clearance deals that you saw 3 or 4 years ago because Target understands that people would literally come into our stores just to buy a ton of clearance to re-sell on ebay and the like. Hell,i still have at least 4 or 5 dealers who come in every morning and shop the stores clearance and they openly admit to me they are re-sellers.
EDIT: and YES, these inventory control methods apply to the whole store in general and not just video games. When they literally receive trucks 5 times a week just from their distribution centers it is easy for them to deduce they only need to send X amount of each product each day/week to satisfy customer demand and no more then that. As for video games, most of it comes by UPS/FEDEX and therefore a bit more tricky to control inventory, that is why you always see empty game cases at Target. They would rather be out of stock on any given item then overstock them by 50 games and have to clearance out 20 of those.