I once spent an afternoon analyzing 7-2 with Poker Probe (An old program by Mike Caro). I was curious if there was any situation that justified making a call with 2-7. PP was a pretty simple program, you could run a hand against a configurable hand, or a number of random hands. It for example could tell you how often a particular hand would hold up against a particular number of players. It did not account for anything but the cards.
My conclusions at the time about 2-7 where pretty much the obvious, it should never be played. 2-7 even suited has such a low rate of return that it simply should never be played.
The more players in a pot the lower the EV is with the hand.
The only situation I could find were you could actually place a chip in the pot and get a slight positive EV on that chip was when your were against one opponent and could get five to one on that chip. If the blinds are ten and fifteen, and you are in the small blind you have a slight positive EV for the five dollar call when head up, if there is another limper in the hand the EV goes negative for the five dollar call. This EV is so low, just a very low percentage like 2 or 3 percent that factors like rake and the bad position your in, the possibility the BB raises, make it a negative play. Even in a time game the time you waste playing the hand might eat up any positive EV.
I looked at a lot of hands and none play as bad as 2-7 against a large field. However that really is not an answer to your question because 2-7 has an advantage over a lot of hands like 5-3, 6-4, 3-4, and other hands that may play better then 2-7 against a larger field.
I think it is safe to say that when compared to all other hands, that 2-7 is the most unplayable hand in poker. Being the lowest possible unconnected two cards the hand never gets the number of outs as even two smaller cards that are a little more connected.