How can a cricket team batting second be automatically eliminated via NRR?

Question

I found this from Cricbuzz and other popular sports site.

I don't understand that last sentence which is "If Pakistan bowl first, they will be out of the semi-final race even before the first ball is bowled at Lord's on Friday.".

Why they can't limit Bangladesh for around 300 runs and make it using just 20 overs or something doesn't qualify for semi, even Pakistan can beat Bangladesh by 311 runs after posting 350 make them semi-final?

For Pakistan to qualify to the semi-final...

Pakistan to beat Bangladesh by 311 runs after posting 350

or

beat Bangladesh by 316 runs after scoring 400

or

beat Bangladesh by 321 runs after scoring 450

If Pakistan bowl first, they will be out of the semi-final race even before the first ball is bowled at Lord's on Friday.

Team	Played	Won	Lost	No Result	NRR
Australia	8	7	1	0	+1.000
India	7	5	1	1	+0.854
New Zealand	8	5	2	1	+0.572
England	8	5	3	0	+1.000
Pakistan	8	4	3	1	-0.792
Sri Lanka	8	3	3	2	-0.934
Bangladesh	7	3	3	1	-0.133
South Africa	8	2	5	1	-0.080
West Indies	8	1	6	1	-0.335
Afghanistan	8	0	8	0	-1.418

Answer 1

Before the Bangladesh match, Pakistan have scored 1710 runs from 338.5 overs and conceded 2073 runs from 303.4 overs. Even given a very unlikely scenario:

• Bangladesh bat first and are all out for zero.
• Pakistan score the one run they need to win without facing a legal ball (no ball, wide, etc)

Pakistan's numbers will now be 1711 runs from 338.5 for, and 2073 runs from 353.4 overs against (all out always counts as the full allocation of overs); this gives them a net run rate of 0.036, still less than New Zealand's 0.175 (the table in the question doesn't include New Zealand's loss to England which significantly reduced their NRR).

There is in theory a scenario in which Pakistan can qualify if Bangladesh bat first, but it's so ridiculously stupid that the ICC would definitely get involved:

• Bangladesh score a four off every single ball in their innings, giving them 1200 runs.
• Pakistan somehow score those 1200 runs without facing a legal ball - e.g. every ball is a wide and hit for four.

Pakistan now have scored 2911 runs from 338.5 overs and conceded 2973 runs from 353.4 overs. This gives them a net run rate of 0.185, above New Zealand's. (The number doesn't quite need to be 1200 runs here, but it's above 1100. Even a vaguely reasonable score like 300 doesn't get the job done).

Answer 2

Pakistan needs to beat Bangladesh with much more than 300 balls to spare. That is why if Bangladesh chooses to bat first, they cannot qualify as the maximum number of balls is 300.