Never has so much been required of so few.

That's how it has seemed watching Bangladesh bat during this Champions Trophy campaign.

At their best, with batsmen like Tamim Iqbal or Mushfiqur Rahim going well, they have looked a class act.

But the rest? They've contributed almost nothing with the bat. And eventually, if you have four men doing the job of eight or nine, the strain is going to tell.

What this tournament has illustrated is Bangladesh's over-reliance upon Tamim, Mushfiqur, Shakib Al Hasan and Mahmudullah with the bat. While all of them have averaged over 40 - Tamim and Mahmudullah have both averaged in excess of 60 - their seven colleagues in this match contributed just 158 between them in 16 innings during the event.

These four are the pillars of the Bangladesh batting. They are the men around whom Bangladesh can build for the future. They have, between them, contributed two of the three biggest partnerships in the tournament and three of the nine centuries.

But unless the joins between the pillars are stronger, the edifice will still collapse. As Mashrafe Mortaza, who weathered a well-directed barrage of short deliveries when he came in but contributed a gutsy 30, put it after the game: "We can't just ask them for runs all the time. It would be nice if some of the youngsters joined in."

Ahead of this game the Bangladesh coach, Chandika Hathurusingha, remarked that his "tail-enders are not batters, they are bowlers." It's a decent soundbite and he can't be blamed for trying to ease the pressure on his side ahead of a big game.

But in modern international cricket, it doesn't really work. Bowlers have to be able to contribute a little with the bat. Especially if one or two (or three, in the case of Bangladesh) of the top seven are out of form or still finding their feet in international cricket.

Bangladesh don't just have the tail of a tiger - Rubel Hossain, Mustafizur Rahman and Taskin Ahmed all average under 6 with the bat in their ODI careers - but they have holes at the top of the order, too. In this tournament their No. 1 and No. 3, Soumya Sarkar and Sabbir Rehman, have averaged 8.50 and 14.75 respectively.

Compare that to India. Quite apart from the fact that two of their top three average in excess of 100 (and the other one, Shikhar Dhawan, averages 79.25), at No. 8 they have a man, Ravindra Jadeja, with three first-class triple centuries (and 10 ODI half-centuries), while at No. 9 they have a man, R Ashwin, with four Test centuries. The result? They always have the ability to rebuild and the top order are encouraged to play bold cricket in the knowledge they have a safety net.

Bangladesh have no equivalent of Chris Woakes who, twice in the last 12 months, had contributed half-centuries from No. 8 to turn games for England. They have no equivalent of Mohammad Amir, who came in at No. 9 and helped Pakistan into the semi-finals with victory over Sri Lanka in an unbroken 75-run stand. They have no Plan B, no safety net, on insurance policy. The pressure on their top order is therefore immense.

This performance will hurt Bangladesh all the more for the fact they lost two key wickets -Tamim and Mushfiqur - to the part-time bowling of Kedar Jadhav.

"We'll do better in 2019. Physically and in terms of skill, we've not been too bad. But maybe we could be a bit more ready mentally to play this sort of game."
Mashrafe Mortaza

It was a brave call from Virat Kohli to introduce Jadhav into the attack. For those who haven't seen him bowl: picture a 60-year-old Lasith Malinga playing in a charity match. The arm is low, the pace is slow and the action just about the opposite of repeatable. Kohli admitted he "doesn't bowl much in the nets".

But that's part of the point. Bangladesh hadn't prepared for this exam. Jadhav had only bowled three overs in the tournament. He hadn't taken an ODI wicket since October. While they had been cramming for the challenge of Jasprit Bumrah and Bhuvneshwar Kumar, suddenly they were thrown an unexpected challenge. It was like preparing to face the Minotaur only to die from a paper cut on your way to the fight.

Jadhav's first over only cost six. It felt as if India had stolen a low-cost over and as if Bangladesh had failed to take advantage. After four dot-balls in his second over Tamim's frustration got the better of him. Feeling he needed to exploit the unexpected opportunity against a lesser bowler, he attempted an anxious slog-sweep only to lose shape on the stroke and, as a consequence, his bails. It was a classic case of trying to hit the ball too hard; a classic case of pressure playing its part and, yes, a classic case of good captaincy.

Even worse was to follow. After a fifth Jadhav over had yielded only two runs, Mushfiqur decided he had to intervene. Charging down the pitch in an attempt to get to the pitch of the ball, he was instead greeted by a low full toss which he could only smear to mid-wicket. It left Bangladesh five wickets down with almost 15 overs remaining. And with a No. 7, Mosaddek Hossain, with a top score of 15 in the tournament and only one half-century on his career, that was an uncomfortable place to be.

Kohli later had the grace to admit he came up with the idea in conjunction with MS Dhoni and conceded the wickets were "a bonus".

"I just thought he had the ability to get in two or three dot-balls to the left-hander every over," Kohli said. "The wickets were honestly a bonus. It ended up changing the whole game for us."

"I think they felt they had to go after him as he is a part-time bowler," Mashrafe said with a sigh. "I thought we could score 330-340 easily at one stage, but it was always difficult once we lost two wickets to a part-time bowler."

It all meant that Bangladesh finished with a total every bit of 80 or so below par. And, against this opposition on this surface, even 370 might not have been enough. Bangladesh didn't bowl especially well but they were always chasing the game. Their batsmen had simply given them too little to defend.

Where does all this leave Bangladesh? To defeat New Zealand in the manner they did, under pressure and from a tricky position, was impressive. And to reach a first semi-final, just two years after that first World Cup quarter-final, underlines their progress.

But any celebration of those facts has to also recognise they won just one game. And the relative ease with which they were brushed aside by India here is bound to take some of the gloss off the achievement of reaching this stage in the competition.

"We'll do better in 2019," Mashrafe promised. "Physically and in terms of skill, we've not been too bad. But maybe we could be a bit more ready mentally to play this sort of game. We need to learn so many things. We are still improving.

"But the boys will learn. The same young players will be back in England [for the World Cup in 2019] and they'll do better than this time. And once you are ready mentally, anything can be possible."

So, it is a disappointing end. But if the young players can learn from the exposure to the conditions and the competition and the more experienced players can retain their fitness and form, there's no reason Bangladesh should not return to England in 2019 better than ever before. It didn't feel like it today, but they're heading in the right direction.

George Dobell is a senior correspondent at ESPNcricinfo