The Brazilians looked to be walking away with the league at the half way stage but have struggled for results in 2012 having collected just twelve points from their last eight matches.
Mushekwi feels their opponents' defensive approach to games means they are harder to break down, hence Downs having been unable to find the net in their last three games.
He told the club's official website: "Things have been a whole lot tougher for us in the second round and clubs are making it harder for us to penetrate them.
"Most teams are always hoping catch us on a counter attack, while some are content with only walking away with a point against us and that makes things difficult for us because we are always facing defensive sides.
"We are playing good attacking football but there are no goals to show for it, simply because teams have become increasingly defensive against us, which means we have to capitalise on set pieces because scoring from open play is made harder by the opponents' defensive tactics."
Sundowns are currently level with Orlando Pirates at the top of the standings with 43 points from 23 games, but they don't play until next week as their featured opponents Black Leopards took part in the CAF Confederation Cup this weekend.