Younis is right. If the top 3 batsmen are performing so well, middle order will hardly get a chance to bat. Either they have slog/hit out, or they are under pressure to rescue the innings. They can not play with the freedom that those at top can play. And those at the top e.g. Rizwan, Imam will struggle down the order as shown too.
We see the same problem with India, their top 3 is so reliable, the rest of the batsmen struggle to do anything/make an impact.
In this situation, you I can see the sense of playing really aggressive middle order batsmen as they will usually come in with pressure to score. I'm not surprised we are playing Asif and Haider (but was surprised when Haider didn't play earlier) as a result. As when both come in, there's almost always pressure to hit quick runs. And while both have failings, both score at high SRs and can hit early on. There are people down the order like Kushadil, Iftikhar, Faheem, Shadab who average low and struggle to hit from the start.
The LOI game has changed, teams are way too top heavy, the game is decided by the top 3, pitches are flatter. Batting middle/late order is now way harder than top order. I think it's fine give players mid/late order extended chances, as long as they can score at good SRs, and preferably hit from ball one. Better to fail at least not playing selfish and going for it, than a slow innings down the order which hurts the team. We just don't need the rescue batsmen mid/late order anymore. And hitters that perform reliably in domestic mid order, I can't honestly think of any stand outs apart from Haider, Asif and Iftikhar to an extent. That is why we're stuck, these guys might be bad, but they are the best from domestic, PSL, the others are probably even worse.