There have been several occasions in the past three years when the Bangladesh Cricket Board (BCB) could have removed Mushfiqur Rahim as Test captain but the clamour for his sacking, even within the board, has been at its loudest during the Bloemfontein Test. So what has happened in the last 11 days in South Africa to prompt these calls?

First, it was how he flouted common sense to field first on an evidently flat pitch in the first Test in Potchefstroom. Mushfiqur said at the toss and after the match that he took the decision to give his bowlers the best possible use of conditions, but it was clear that he didn't have confidence in his batting line-up, which had done poorly in their previous Test, at home against Australia.

In Bloemfontein, he took the same decision on a pitch that required batsmen to be courageous enough to handle the first two sessions before it eased out. Given the opportunity to do so, South Africa made full use of it, posting 428 on the first day itself.

Both these decisions weren't received well by the BCB, and Mushfiqur gave his bosses a second reason to think strongly about removing him as captain. On that first day, he broke the usual practice of sending other players to the end-of-day press conference by attending it himself. Once there, he didn't just defend his decision to bowl first, he also said that he had failed to motivate his players. The revelation that the "coaches" asked him to field in the deep instead of fielding positions close to the bowlers also didn't go down well.

Before play began on the second day in Bloemfontein, BCB president Nazmul Hassan said he couldn't find any justification for Bangladesh deciding to bowl first.

"You have to bat first in this pitch," Hassan said. "I think only Mushfiqur can say why he took this decision. If I say during a match, he will get nervous. I spoke to him on the phone but I didn't tell him anything about this. I thought he'd decide to bat first. I was really surprised with his decision at the toss yesterday. Maybe they saw something that we can't see from here."

Hassan's words are the tip of the iceberg that's approaching Mushfiqur in the coming weeks. Most of the support the board gave him evaporated after the Chittagong Test against Australia last month, when he said it was not possible for a wicketkeeper to bat at No 4.

The BCB were particularly irked by that statement considering how it has supported his cause as a captain-keeper-batsman. He was trusted with the gloves in Colombo this year even after Liton Das was named as the frontline wicketkeeper. But these tactical errors - carrying on from those he made in Bangladesh's previous Test, when they kept feeding a rampant Nathan Lyon left-handed batsmen to prey on - may have turned the tide against Mushfiqur. Hassan criticised him for that at a private meeting.

There have been several discussions about Mushfiqur's triple role in the Test team, and now Bangladesh may finally relieve him of the captaincy. Considering how Liton has started to prove himself as a wicketkeeper, Mushfiqur might soon find himself playing as a specialist batsman.

These changes could have come in September 2014 when he first lost the limited-overs captaincy. But the lack of viable alternatives meant Mushfiqur remained Test captain at the time.

Mashrafe Mortaza's excellent record as ODI captain also began to undermine his Test captaincy. And the first major alarm came after he chose to bowl first on a slow and flat surface in Dhaka in the second Test against Pakistan in 2015. Bangladesh lost that game by 328 runs, but given the team's maiden ODI series win over Pakistan, the BCB didn't want to kill the good vibe by sacking an in-form batsman.

Mushfiqur's Test captaincy entered its strangest phase when coach Chandika Hathurusingha asked him to step down for one session last year. Under Tamim Iqbal, Bangladesh bowled out England in the third session of the third day, which resulted in their maiden Test win over that opposition.

It should have been enough for the BCB to remove Mushfiqur as a captain. The team management was certainly not happy with the job he was doing, and had replaced him in the most crucial phase of that Test match. But it was felt at the time that the BCB didn't want the uncomfortable headlines of replacing the captain who had been officially in charge when Bangladesh beat England in a Test for the first time.

Bloemfontein is Bangladesh's last Test this year, so 2018 is likely to start with a new Test captain. Tamim is emerging as the leading contender for his form and seniority, and also given the uncertainty about Shakib Al Hasan's Test future. Mahmudullah would be another name on the table but his fluctuating form will work against him.

Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84