Shelvey has had an up-and-down season at Swansea, impressing at times in the club's rise to eighth position in the Barclays Premier League but also guilty of some below-par performances which have seen him lose his first-team place in recent weeks.
The 22-year-old former Liverpool man was sent off against Everton at the beginning of November and his start against Hull on Saturday - in which his 25-yard drive deflected off Ki Sung-yueng for Swansea's winner - was only his second since that Goodison Park red card
But Swansea boss Garry Monk insists Shelvey, who won his solitary England cap in October 2012 but was part of Roy Hodgson's squad this autumn for Euro 2016 qualifiers against San Marino and Estonia, has "frightening ability" and could play for one of the country's top six clubs again if he matures on the pitch
"I think we have only seen about 50 per cent of what Jonjo can do," Monk said ahead of Aston Villa's Boxing Day visit to the Liberty Stadium.
"We need to get him in the right place physically and mentally to be able to do it
He is still very young, which a lot of people tend to forget because he has been around for so long.
"He might just need to do a bit of growing up in terms of the maturity in his game and recognising certain things a bit more because that ability is frightening when you work closely with him.
"If we get that right and work with him closely we will have a top-six player on our hands."
And Monk believes Shelvey does not have to look very far to see what can be achieved if he puts his mind to it
Icelandic playmaker Sigurdsson signed on for a second spell at Swansea last summer after two seasons at Tottenham where he often found life difficult.
But Sigurdsson's form since returning to Swansea has been nothing short of sensational and with eight assists he is second only to Chelsea's Cesc Fabregas in that particular Premier League list.
"Gylf is a perfect example for Jonjo," Monk said.
"He built himself up, went to a big club but it didn't quite work out for him at Spurs.
"He's come here, worked extremely hard at his game and delivers that performance you're looking for.
"It's something for Jonjo to look at because ability-wise he's up there with Gylfi and can be as good, if not even better
He has to follow that lead."
Shelvey should get the chance to impress in the new year with Ki set to miss possibly as many as six Swansea games when he is away at the 2015 Asian Cup in Australia leading South Korea.
"We will want him to step up and if you get the opportunity you have to take it," Monk said.
"I speak to Jonjo a lot and he knows what I expect from him.
"It is about pushing him to get him right mentally and physically and hopefully he will deliver."
Source : PA
Source: PA