^^ Both Umar & Amin.
The idea is to play 3 attacking players, who can reach 100+ SR by 35th ball on a 300 per ground & one master player to hold the innings at a decent SR, which has to be over 80, good if it's 85+.
2nd objective is good diversity in batting order, at least one lefti (or 3, other way) in top 4, better if it's 2/2. Both Umar & Amin has the game to hit boundaries - if we analyze Fawad & Amin's innings, actually Fawad had a better SR, for his outstanding shot productivity (opposite to dot ball %), while Amin hit 5 Sixes, I believe. Both are on same ground & against same attack, which indicates individual hitting ability. Between Fawad & Haris, I'll always take Haris, because of his power game, though Fawad adds much more in fielding & running, both are probably at same level with ball.
Problem for PAK openers (Ahmed) is that, they simply can't hit boundaries against decent balls, while half of the loose balls ends like a trace of bullet to an inner fielder, too good even to get a single. Kamran's problem is that he is too limited technically & in array of shots - one good day he'll blast 40-50 at 140+SR, but he is not the guy to score 100 or 125, technically too limited to score against spinners or against 4 fielders at line. Fakhar is a mix of both KAkmal & Ahmed - he has good shots, but extremely limited in options; in both matches, he slowed down considerably after the PP, because of lack of proper shots in his stock.
PAK is determined to bring Umar & Azhar in the squad, therefore I see best use of Umar as opener, at least he won't do Azhar or Shezad like damage. However, since MoHa is destined to start, he should open with Amin, BUT, he must he talked 1-2-1 regarding his role as opener, his motive as a senior player & expectation. In these days of 300+ per ODI, there are several openers in PAK who can score a nice 38 of 58 balls, playing entire PP.
So far, in both chases, it's evident that top 3 are playing for their score, rather than what is possible & what is expected in last 25 overs. At this level, I don't think any player is that dumb not to realize that slogging has an elasticity - no matter how many wickets are at hand, max 200 in last 25 overs is possible to chase, that too on a 350 wicket; which in other words, at mid point (25 overs), 150 is bare minimum to chase anything over 325. Better, 150/1, if not 153/4 is better than even 111/0.
Another interesting development in the game that I have noticed is that, the game has altered it's role for top 6 players - apart from very few like Viv or Zaheer; in first 35 years of ODI, batting strategy was that, KPI for top 3 is average - batsmen batting in top 3 was expected to have high average, so that they can hold on to the innings for a considerable period while KPI for batsmen coming at 4-7 was SR - they were expected to blast a quickfire 20 or 30. For that, players like Kapil, Razzak, Afridi, Cairns were like gold. Now the role has altered - teams are looking for a blasting start from top 3 & consolidation from next 3-4. Off course, there are AB, Smith, Kohli, Roots .... who can do both.
This is because of change in context - chasing 250 on a difficult wicket, I would like my top 3 to take at 180/3 by 40 overs, so that next 3/4 can blast towards win in last 10 overs. Chasing 350 on absolute belter, even 240/3 after 40 would result in a close miss - simply because of slogging elasticity, one can't expect to maintain 12+/over for 10 overs; in other word, every dot ball means next ball requirement is a boundary, which is impossible for 10 overs. Now the strategy is to reach even 290/7 in 40 overs & then one set player can anchor to the target with the help of tail, who are decent these days for run a ball situation on such batting conditions (it was always like that - Wasim, Warne or Marshal would have doubled their average in such condition).
This is the biggest missing link in PAK LO team, which sadly is way behind in thoughts & ideas. Even SRL, BD, AFG, WI, IRL or ZIM are loading their top 4 with blasters, may be one grafter like Tamim or Bravo - PAK is trying with Azhar, MoHa, Malik, Sarfu, Shehzad & Babar in top 5 in various orders. It's still better than having Shehzad, MoHa, YK, Misbah, Fawad, Sarfu in top 6. BUT, now that top 4 MUST have to be fixed. I don't mind Ahmed or Azhar opening - BUT, with a specific target for PP, otherwise next match drinks trolley ........