Agree with you there Al. I think the problem probably goes a bit deeper than just Mackie though. Until Aluko was playing up front, the choices to partner Miller were Maguire or Mackie. The two of them are just different shades of shit, as far as I'm concerned and I'd probably pick Mackie out the two. JC then said at one point earlier in the season that for the next "X" matches his front two would be Miller and Oor Barren.
Now, if that's the case, it shows Mackie that he can play badly and still be picked, conversely, if he scores a couple he'll also still be picked. If we got a genuinely decent striker in to partner Miller, I wouldn't mind if Mackie hung around as backup, but as a first choice striker he's certainly hampering us.