Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84
Bangladesh have certainly shown that they are a much-improved Test team, and so their collapse on the fourth day - slipping to 97 for 6 - was an opportunity missed. The opportunity to win a Test series against Australia. The opportunity of a generation.
They had stood firm in more difficult circumstances earlier this year, in Wellington and in Colombo. Their bout with India, the No. 1 team in the world, was definitely not pretty for the bowlers but their batsmen showed themselves capable of fighting back. Having been made to follow-on, Bangladesh lasted more than 100 overs, making R Ashwin and Ravindra Jadeja earn the eventual victory.
Chittagong, though, was a disappointment. Trailing by 72 runs when they began their second innings, none of the top five could make more than 15 runs. It didn't seem like they lacked for technique but more the mettle to handle a difficult situation. Nathan Lyon had spooked them in Dhaka, and he was playing on their minds again when proceedings at Zahur Ahmed Chaudhary stadium were barely an hour old. There was no turn off the pitch and yet they lost three wickets in the first session - all to Lyon, all off straight balls. It appeared like Bangladesh were in denial, as if they thought they had no weaknesses in playing spin.
They also didn't have a settled middle-order. Four different batsmen were used at No. 4 - each one given only one innings yielding a top score of 31. The seniors Shakib Al Hasan and Mushfiqur Rahim also exchanged positions at five and six. They finished the series with a specialist No. 3 batting at No. 8 but Mominul Haque's demotion, it turns out, was part of a strategy meant to deny Australia's bowlers a steady diet of left-handers.
"We had planned to mix up the batting orders," Mushfiqur said. "It wasn't based on what someone did in the previous innings. We gave each of them a game plan but if they can't execute it, the team management can't be blamed. We were not getting what we expected from Sabbir [Rahman] at No. 4 so when he did well at No. 7 in the first innings, we kept him there. Shakib always plays at No 5. We had three openers in the top-order so we couldn't change that. We wanted to send out a right-hander to make it harder for them."
On the bright side, Mushfiqur did feel that Mominul was impressive against Lyon. "I think he handled the best offspinner in the world very well and showed to those who said he can't play offspin. I hope we keep these things in mind when making the combination next time."
The team management might have seen the Dhaka pitch and realised it would turn big. So they would have liked Sarkar as an attacking option at the top of the order. After all, he had already struck four Test fifties in 2017. However, his lack of footwork put paid to those ideas, finding life especially difficult against Pat Cummins, who had him caught behind twice in four innings.
In the first Test, with 11 balls to stumps on the second day, Sarkar danced down the pitch and holed out in the deep for 15. In Chittagong, despite looking out of nick, he lasted over two hours in the first innings before he was dismissed for 33 by a non-turning offbreak from Lyon.
Touch players can be a pleasure to watch, but the moment there is a problem in their hand-eye coordination, things can do downhill quickly. Sarkar found that out against Australia, finishing the series with 65 runs at an average of 16.25 amid chatter that his place in the team as in danger. And then was knock-on effect as well.
Kayes, who had admitted he wasn't suited to No. 3, looked out of sorts all series. His final act was a soft poke outside his off stump to be caught at point. On another day, he might have left that ball well alone. Now there is debate over whether he is needed in the team, as is bound to happen when a player scores only 21 runs over four innings. With numbers like those, will he be able to command a place in the squad for the next assignment, a tour of South Africa?
There will be similar questions asked about Nasir Hossain, who was dismissed by left-arm spin in all four innings, a style of bowling Bangladeshi batsmen grow up facing and one practiced by South Africa's lead spinner Keshav Maharaj.
Sabbir Rahman made his highest Test score of 66 in the first innings in Chittagong, which might probably work in his favour, and he would need that after his dismissal second time around, when he charged out of his crease looking to attack, then inexplicably changed his mind to try and defend and was eventually stumped by a long way. Then again, taking on the bowling is Sabbir's role in the team and he is generally quite good at it.
Mushfiqur had highlighted the importance of the rest of the team pulling their weight, and not relying on Tamim and Shakib to produce match-turning performances. Such was the case in the second innings in Chittagong and there was no back-up to be found.
"We had a chance to draw the game in Galle earlier this year," Mushfiqur said when asked to comment on Bangladesh slipping up in key moments. "In these critical situations, we end up having one really bad session which makes it hard for us. I think we lack maturity and there are some technical problems too.
"This adds to the lack of confidence when you are trying to play defensively. We have room for improvement in terms of our technique. Warner was a great example in front of us. He is an aggressive batsman but he probably scored his slowest hundreds this time."
Bangladesh have shown, since their resurgence in 2015, that they can get out of trouble given time. The problem is, their next tour is in South Africa and it is in less than two weeks.