It's easy to say "if Manly didn't drop the ball here, didn't do a high risk offload their, didn't get bundled into touch, didn't give away penalties at the back end of a tackle set" etc etc but that is what pressure does to teams and Melb consistently achieve better in those stats than any other team.
When Manly achieve low errors, low missed tackle counts and low penalty numbers it is seen as our perfect exception to the rule game, when Melb achieve the same numbers it is seen as business as usual----or "the NRL sides with Melb for the past 14yrs"
Problem is when you overly focus on low error counts that in itself applies it's own pressure and you start to play with tension or within yourself---you know you can't beat the Storm with high error rates but you also know you can't beat the Storm going into your shell and playing low risk footy.
Manly just have to play their game no matter what and just allow the natural improvement and confidence of the team to reduce our error count or compensate with good attacking execution that builds pressure on the Storm with points.