After starting the AFL season with five tight games, the Saints were blown out of the water last week with a 10-goal loss.
Lyon said one of the keys to the blowout was the Saints experimenting with their team defence and sitting off the Bulldogs more.
"We were pretty passive in defence," he said.
"We made some tactical errors ... that's the reason they had their 135 uncontested marks, which we owned as a coaching group.
"We got pulled apart a lot, which is not typical of us. We made a tactical error and it was hard to fix, so I'm owning that and my coaches, we own that.
"You're paid to get it right."
Port were also shown up by Collingwood last weekend, leaving two teams with plenty at stake in Friday night's Adelaide Oval clash.
"It's critical, isn't it? Port have been stung as well," Lyon replied when asked about the need for a quick response.
"We're pretty keen to get our energy back, so we've had a few days off. They're pretty vibrant.
"Until last weekend, we were pretty proud of our efforts. But if we really drill in, we're inconsistent barring maybe one or two games - contrasting halves.
"We're trying to get a four-quarter performance of the sort of footy we want to play."
While acknowledging St Kilda deserved the blowtorch over the last few days, Lyon added they need to stay upbeat.
"They were a bit flat, so I said I've been in deeper holes than this. I think that lifted them," he said.
"That's why we come in (to work), don't we? The stress is part of being alive."
There has been some good news this week with impressive newcomer Darcy Wilson named the Rising Star nominee and key forward Max King likely to resume from his knee injury.
"It's not guaranteed, but it's looking more likely," Lyon said of King.
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