At the moment, he doesn't deserve to be in the playing XI, forget captaining the side.
He is an average bowler, whose bowling has been repeatedly exposed against the big teams, his batting is barely a level above the likes of Faheem Ashraf, and his great fielding doesn't warrant him a place in the team if his bowling or batting don't win us games.
As an all-rounder, he is a few levels below Imad, who has been our best all-rounder since Afridi's retirement and deserves to captain the team during Babar's absence.
Both Imad and Shadab bat at 7-8, a position where we need a power hitter, capable of going at 150+ in the last overs. Imad is easily the better hitter. Shadab strikes at less than 70 in ODIs, which is pathetic, even more so if he bats at such a critical position where his strike rate has to be 95+.
Even if we consider him as a bowling all-rounder, his bowling has been nothing special against the big boys. Yes, he might take a wicket here and there, but mostly when batsmen will be looking to smash him out of the park. There is a reason why his bowling average is close to 50 against non-minnows. Unlike Shadab, Imad rarely gets smashed and his fulfill his bowling role quite well, which is bowling a tidy spell, with a wicket or two as a bonus.
