If he's just as consistent, it won't be a problem. The thing is, I wouldn't open with Abdullah, I'd open with Haider. Babar could do what he does in the powerplay, but Haider can be the raw aggression which we so desperately need. If anything goes wrong, Abdullah can come in at 3 to play cool headed cricket with Babar. Hafeez can come in and do what he's been doing for the last few years. And then our middle order will have to finish the game off.
Just observing Abdullah’s game in the National T20 cup, he always did well coming in early during the powerplay rather than in against the spinners. I think his stroke making is quite tantalizing as it means he can make use of the field setting the way Babar does. Haider will then come in later on when he can bash the spinners with Hafeez to consolidate the middle overs. If we were to add Azam Khan at 5, that would give us some momentum between overs 10-15 if he faces, say, even 15 deliveries to hit 25+ runs.
That’s how I see the best combination working out. On average we should aim for a game like this:
1. Babar 50(35) SR 142
2. Abdullah 30(22) SR 136
3. Haider 30(18) SR 167
4. Hafeez 40*(26) SR 154
5. Azam 25(15) SR 167
6. Khushdil 10*(4) SR 250
Did not bat: Imad, Shadab, Wahab
185-4 in 20 overs
I don’t think it’s super unreasonable as long as everyone chips in, with three remaining players in Imad, Shadab, and Wahab to cover our bases if we lose wickets before individual players achieve their respective targets. And there will be games where Babar, Haider, Abdullah, or Hafeez get set and go bigger than the scores listed above to compensate if the others get out.
So I don’t think this is an unreasonable strategy to consistently scoring a top class total in T20s.
That’s how I would design a role-based team. Everyone has a defined role - in this case Abdullah’s role is to bat out the new ball and not worry too much about SR, just give the team a stable base with Babar. Make use of the field setting when and where he can.
Haider and Azam are acceleraters, given the free rein to play their naturally aggressive game in overs 6-14, with Hafeez to consolidate around them. Khushdil to come in late game and smash a couple big sixes down the leg side.
The alternative strategy is to find an attacking opener to partner Babar in the vein of Fakhar - this was necessary during our number 1/UAE years because of a lack of SR in the middle order, otherwise if you look at how KL Rahul or Rohit Sharma or Shikhar Dhawan or Virat Kohli bat, they aren’t actually always that quick in the powerplay even on batting tracks against relatively inexperienced bowlers.