It's quite probable that I'm just emotionally invested in the chase for 4th now. I think if you do the probability math, though - winning a "knockout" competition is less likely than finishing 4th. I don't think we have the depth to seriously challenge for both. We could stretch ourselves thin chasing the Cup, lose in, say the semis - and in turn end up 7th in the league. That would leave me pretty gutted.
It's sort of the flip side of what Moyes did, conserving resources for the Cup when it was plain that it would be almost impossible to finish better than 7th. Although I'm sure that was...ahem, a tad controversial at the time (I wasn't clued into this forum yet).
Of course, we may in truth not have enough healthy flotsam to properly rest our squad for the Shite anyway. So this is likely just an academic discussion. Got to kill time until Saturday somehow, right?