Key word being striker, which we don't have. Also the idea of playing ..
..........................gk........................
rb.................. cb ...... cb.......... lb
..........................dm
......................cm...... cm
rw........................................... lw
..............................st
is that the striker holds it up and brings in the wingers, creating the goal. I agree with the second part though, there is a time and a place to be greedy, but against united it definately isn't.