Arriving at the Blues with the financial help of a third-party deal, Marshall is in danger of becoming a bit-part player. He must work hard to put aside the frustration and impatience he has to be feeling after proving himself time and again on the tough league fields of Australia and New Zealand.
A bubbly character on and off the field, Marshall, 29, must take a long-term view after admitting to struggling with the differences in his new code.
In the Blues' four matches this season, his opportunities have been limited to: 20 minutes v Highlanders, non-playing reserve v Crusaders, not named in squad v Bulls, and 80 minutes v Lions.
His latest experience would have been bittersweet. A well-taken individual try at Ellis Park, after he dodged several defenders, mirrored his former exploits in the 13-man game, but the satisfaction of helping his team get close against the Lions will have been dashed by the disappointment of missing out on a starting spot tonight.
"I enjoyed it," he said this week of the Lions match. "It was good to get out on the field and play the full 80, I haven't done that before. I was happy with how it went, apart from losing.
"I feel like I've learned a lot from watching during the two weeks I didn't play. I've probably had to be more patient than I expected, but that's all part of it. I always said to JK, if he didn't think I was up to the job to not put me in there and he's stuck to that and gave me a chance [last weekend] which I tried to take with both hands and I really enjoyed it."
Asked if he thought his progression to rugby would be relatively straightforward because of his skill at league, he replied: "I hoped so ... technically there was a lot more to learn [than expected].
"Playing 15 has given me more opportunity to learn at 10 as well so whatever happens I'm ready to go."
The Lions were supposed to be one of the weaker teams this season after not playing Super Rugby last year but their victory over the Blues and their earlier wins over the Cheetahs and Stormers have proved there is no room for experimentation in this competition.
After tonight's match the Highlanders visit Eden Park, hoping to make it two from two this year. In a fortnight Kirwan's men face a tough trip to Canberra to play the Brumbies.
Marshall's opportunities are likely to be limited. Try as he might in training and off the bench, his immediate prospects of more game time are out of his control.