The hooker has enjoyed plenty of game time this season, making 20 appearances so far, with eight of those being starts.
He was in from the off against Gloucester last Sunday, scoring a second-half bonus-point try for his team.
And Marshall said: "It (this season) has been a funny one.
"I started out with an injury and didn't get much of a look in but a couple of lads got injured and I've had plenty of game time.
"It's been a season for me that has given me games on the bounce and it's nice to establish myself as someone who can be trusted now and is a strong squad player."
With Dylan Hartley, Mike Haywood and James Fish currently injured, it was up to Marshall and recent short-term signing Darren Dawidiuk to shoulder the burden at hooker last weekend.
And Marshall has enjoyed working with Dawidiuk, who at 31 years old has a wealth of experience, having made more than 100 appearances for Gloucester.
"I really like Dukey," Marshall said.
"He's a really nice guy, really helpful, passes his experiences on and you don't get 100 caps for Gloucester not knowing your stuff.
"He's helped me out with my knees, tendons and stuff in terms of my injury rehab, anything scrum wise and he's been more than helpful."
Saints were unable to get the win they desperately wanted last weekend as Gloucester scored six tries on their way to a 40-31 success at Franklin's Gardens.
It means Saints have now shipped a total of 101 points in their past two matches, having lost 61-38 in the European Challenge Cup quarter-final at Clermont Auvergne a week earlier.
And Marshall said: "It's been up and down.
"There have been some real positives from our attacking form and you can't question our attacking intent but we've conceded a lot of tries as well.
"It's something we're going to have to knuckle down and concentrate more on.
"We've had a sit and chat about it, about our defensive mindset for last weekend, and in hindsight we probably gave Danny Cipriani a bit too much respect last Sunday.
"We went away from what we're about.
"Before Clermont we were pretty good at getting off the line and closing people down and maybe we worried about Cipriani's strengths rather than ours and it bit us."
Saints will now bid to sort out their defensive issues for Saturday's key game at Harlequins.
The black, green and gold are currently seventh in the Premiership standings, seven points behind fourth-placed Quins with four games to go.
"We're only looking up, we're not looking down and that's the way we've got to approach it," Marshall said.
"It's tight down the bottom of the league and it's tight for that top four and anything can happen.
"Quins have come off a couple of defeats and we need to go there with everything we've got now we've blown up the game against Gloucester.
"We need to give ourselves the best chance of top four."