The black, green and gold have bagged three successive away victories, delivering huge defensive moments in each of them.
Last weekend, they pieced it all together, getting through an enormous amount of work, particularly on their own line, as they won 13-12 at champions Exeter Chiefs.
And ahead of Sunday's home game against Bath, Vass said: “I enjoyed the result. It was pretty intense to watch so I didn’t enjoy the end of the game as much.
“But more importantly, the players enjoyed defending. That was the main thing.
“There’s been a shift in our mindset.
"The fact that they come away from that having enjoyed making that many tackles and keeping teams out is definitely a positive we can continue to work on and go forward with.
“It’s been difficult with Covid jumping in and out and trying to build something.
"It’s been hard trying to move forward, you often have to take another step back every time you come back from a break so that’s been tough and taken longer than it would normally.
“It has been coming; little by little, step by step you get better each week and there will be things to fix this week for sure.
“Hopefully that will make things better for Bath. It’s by no means just a one-off but a step in the right direction of how we want to defend.”
Defensive defiance in stats
A massive 74 per cent of last Saturday's game was played inside the Saints half, but Exeter only scored 12 points.
Despite having to make more than twice as many tackles as their hosts (220 to 90), Saints had a superior success rate with 94 per cent completed.
Saints have more than halved their average number of points and tries conceded, allowing only 16.25 points and 1.75 tries per game during this four-match winning run.
Sam Matavesi and Nick Isiekwe topped the tackle count across the entire league last weekend, making 22 apiece against Exeter.