Pakistan began the tournament with wins over the Netherlands and Sri Lanka before losing to India, Australia and Afghanistan.
The last defeat was a major upset as their Asian neighbours won by eight wickets to leave Pakistan fifth in the standings, but Shadab said they can return to winning ways with their backs against the wall.
"I think we have underperformed in all three matches. We haven't underperformed this way before. We know that we are not playing good cricket," Shadab told reporters ahead of Friday's game against second-placed South Africa in Chennai.
"But our team has bounced back from this situation before and hopefully, we will come out of this situation... We have full faith in our team. Our team was playing well before the World Cup.
"We didn't play well in the World Cup. It's not always the case that we, as a team, did not play well. There are bad days, but I think we will start our winning streak from tomorrow."
Pakistan also have a negative run rate to contend with as they fight for a top-four spot and Shadab said the clash against South Africa is the first of many "do-or-die matches".
Shadab identified their fielding as a cause for concern after dropped catches on batting-friendly wickets and also said the fast bowlers were struggling as a unit.
"If you drop the catch or you give an easy boundary, then there is no pressure on the batsman and because of that there is a lot of cost in the end. The way we are fielding is completely different from the standard that we have set," he said.
"These fast bowlers, they performed very well in the last couple of years for us, everywhere they played. We have a faith in them and sometimes... you go through these stages.
"But the main concern is everyone is going (through a rough patch) at the same time. That's a problem... So hopefully it's changed tomorrow and everyone starts on their right track."
