Ma'a Nonu, Francis Saili or Jackson Willison could push out a place to centre but are better suited to their second five-eighth duties while Pita Ahki could do the business but he is new to this level of rugby.
Piutau was sensational in this year's Super 15 at fullback where his aerial skills, counter-attack, kicking and all-action game impressed the All Black selectors. He was supposed to soak up the experience of being with the squad to assist the senior men at fullback and the three-quarter line. When injuries and circumstances intervened, Piutau showed consistent poise and venom as a substitute fullback then on wings.
He has played 10 tests and is one of the stellar talents for the All Black selectors to support towards the next World Cup.
Piutau has shown he can handle multiple positions. Like Israel Dagg and Ben Smith, he has skills which transfer across those duties and he might cope at centre for the Blues.
However, as Ben Smith discovered when he was shifted to take on Conrad Smith's regular duties, there was a great deal to absorb about positional play and defence. All the fire and enterprise that Smith was able to produce at fullback and wing quickly began to fade when he moved infield.
Piutau has marvellous natural talents which are more suited to the space at fullback or the roaming duties on the wing. He gets more freedom there than he would at centre and his naturally expressive skills are crucial for the Blues.
Learning to play centre demands a longer apprenticeship and constant practice rather than occasional forays to help out.
The Blues staff will have sussed out the thoughts of All Black coach Steve Hansen, his assistant Ian Foster and the selection intelligence of Grant Fox to scope out their thoughts about Piutau's future.
He has just started top rugby and needs to build on his first full season with the Blues. The priority must be Piutau and continued investment in him at fullback.
Benji might be box office gold for the Blues but Piutau is a proven star whose gifts have to be cultivated. Then the staff can concentrate on using Marshall as a five-eighth and getting him acquainted with rugby's rhythms.