The 24-year-old has been the Magpies' skipper in Fabricio Coloccini's absence.
The midfielder has been given the armband since Fabricio Coloccini sustained an injury in February, but has only been able to guide the club to one point from six games.
And while that form has helped leave Newcastle second-bottom in the Premier League six points from safety, Benitez has suggested that Shelvey should not shoulder all the responsibility for the club's recent problems.
"I think the team as a team has to improve, and him, as a captain, is training well, pushing, working very hard," he told the Shields Gazette.
"When I talk to him he is trying. He understands, he tries to help, but you cannot do too much if the team is not performing.
"He is trying to give everything and support his team-mates."
With three assists since his January move, the former Liverpool and Swansea man has already established himself as one of the most productive members of the club's squad.
His ability on the ball, especially his distribution, has the potential to unlock defences and create golden opportunities for the club's strikers. However, once that pass has found its way to the person it was intended for, there is very little that Shelvey can actually do.
However, with most of the side's problems coming from their frailties in defence, Benitez may need to decide whether to ask the England international to sit slightly deeper during the final weeks of the season to protect the back-line or whether asking him to focus on defending will have too negative an impact on the amount of chances being created for the strikers.