The Seahawks cruised to a 36-16 victory at CenturyLink Field as the Packers' tackling failed to bring down running back Marshawn Lynch and also gave away costly penalties.
McCarthy told reporters: "We were not sharp. We didn't run through the tackling. I mean, our footwork was poor and when you start leaving your feet to tackle people, it puts you in a compromising position."
The Packers face the New York Jets in their week-two clash next Sunday.