Cricket's most toughest job (or most precious assets) are the fast bowling all-rounders - fast bowlers that make the team with bowling merit & then capable of contributing with bat. Apart from being multi talented, one main reason being the work load that demands bowling fast for 35+ overs/FC match & then bat at 4-6 at FC level - on top of that more than that match time, hard work at gym & nets for developing/maintaining both skills.
Most great fast bowling all-rounders started as fast bowlers & then developed batting. Almost every great fast bowling all-rounder from Giffen in 1890s to Pollock in 1990s actually started career taking the new ball & then gradually moved up from No. 9/10 to even 4/5. Giffen, Monty Noble, Albury Faulkner, Jack Gregory, Ray Lindwall, Miller, Davidson, Peter Pollock, Procter, the fantastic 4 of 80s, Pollock, Wasim, Cairns, Flintoff, even in their last stages Marshall, MoJo & Vaas - all of them started as good to great bowlers and then gradually developed batting skills. Kallis also started career at 7 & 4th pacer of the team. One reason being bowling is more of natural skill while batting is methodical, process oriented & learned/developed trait with time & experience. For example, Stokes can become a 40+ average Test batsman, but he won't be able to bring his wicket/Test to 3.5-4 level, even if he starts to focus entirely on fast bowling at this age. By 25, every fast bowling all-rounder was established world class fast bowler.
In that regard, I think it's easier to develop Amir & Hasan as useful batsman at 8 & 9 with Shadab batting at 7 (even 7 & 8 with Shadab at 6 & Yasir at 10), rather than trying to make 3rd seemer out of Yamin or Fahim - they are just not good enough to replace 3rd seemed. This young Kid Nawaz can become an useful cricketer, if he focuses on his bowling, rather than batting.
LO is played on combination, hence PAK can accommodate both Fahim & Yamin - if they can factor that batting depth (which should put Amir & Hadan at 10/11) in batting strategy; but ala ENG, it's most likely will back fire in clutch matches. Recent times (after their rebirth) Poms got brutally exposed in both their big matches for that "all-rounder" syndrome. Batsmen choked in CT SM, but they simply didn't have the attack to make a match of that low score. For England, it might be out of their hand that both Adil & Moeen happens to be their best spinners, but PAK has better bowling options than playing MoHa, Malik, Imad, Fahim & Yamin in playing XI for their bits & pieces skills, rather than playing 50 overs of relentless attacking threat - icing on the cake is the batting ability of Shadab, Amir & Hasan.
I always put AUS as far better team than Poms (despite that loss in CT), because of the batting ability of their regular bowlers - in past Lee, Warne, MoJo .... now Starc, Faulkner, Pattinson. For the first time, I saw Aussies sacrificing their bowling for "all-rounders", and that didn't work for them - like playing that single digit averaged player batting at 4.
PAK also shouldn't go English way - team composition for PAK is more closer to Aussies than Poms, actually better because of the spin options available. Bowling is the core strength & team combination should be built on that - and then try to squeeze maximum batting efficiency out of bowlers, who can win matches only by their bowling. Bits & pieces cricketer won't suit PAK team.
