Yeah, because amazing plays don't give you lots of points. E.g. Hughes try saving tackle on Montoya is just a tackle nothing more on fantasy.I'm a newbie to fantasy and supercoach and have similar teams but am finding it amusing the huge difference in scoring for some players.
You want guys that do linebreaks, tackle busts, tackle lots etc. Essentially you want guys that stay on the field. If your whole team are 80 minute players then you are doing well, but they also the more expensive guys too.
Though take my advice with a massive grain of salt cause I suck at fantasy