Four weeks of poor performances in South Africa and everyone in Bangladesh cricket is worried about the pace bowlers. The seven matches in that tour, across formats, revealed some home truths about their technique, skills and attitude. Taskin Ahmed, Rubel Hossain, Shafiul Islam, Mustafizur Rahman, Mohammad Saifuddin, Mashrafe Mortaza and Subashis Roy jointly took 19 wickets in seven matches, averaging 83.21 and taking a wicket every 15.1 overs.

Among those who really matter in Bangladesh cricket - senior cricketers, coaches and board officials - there is already an urgency to find out what went wrong. Although the BPL will begin within three days of the team's return home, it is not a topic that is easily going away.

It was one disaster after another in South Africa, starting from the Test series. Mushfiqur Rahim threw the pace bowlers a challenge to eke out advantages from what he perceived to be the first-day freshness of pitches in Potchefstroom and Bloemfontein. But they ended up bowling all over the place, giving South African batsmen at least two bad balls every over.

The twin failures drew the wrath of Mushfiqur, who himself was not spared for deciding to bowl first on batting-friendly pitches. That ultimately led to the sapping of any confidence in the ODIs, a format in which many of these pace bowlers have done well over the past three years.

South Africa followed a 10-wicket win in the first ODI with two 350-plus scores, and continued their dominance through the T20Is, where they batted first in both matches and posted totals of 195 and 224.

The focus of most observations in the last week or so has been that Bangladesh's pace bowlers are not bowling enough during training. Some have said it has become a "bad habit", that the bowlers should simply be putting in more hours at the nets. Instead, the belief is that they spend a lot more time working on their fitness, either running and sprint work or in the gym.

The bowlers themselves, at least privately, also feel they should be bowling more and that the focus as of now is more on their fitness.

"If we are to bowl 10 overs in a session, we cannot be bowling four overs in training every day," one pace bowler told ESPNcricinfo. "It is not a difficult thing to understand that by bowling more in the nets, we will improve. But it doesn't happen like that in the Bangladesh team."

He also spoke of the generally unsettled existence of a Bangladesh fast bowler: they hardly play in home Tests where spinners dominate, sometimes not bowling a single over in long sessions of only fielding in the deep. At the same time they spend months training in the senior team's camps, which keeps them away from bowling in first-class cricket.

That leads into another frustration. Those who have worked closely with the pace bowlers point out that while they work hard, they are not as self-sufficient as the team would like them to be. They stick to doing what they are told, and hardly ever contribute to team meetings. Worse, they don't set their own fields.

Mushfiqur's criticism did not go down well with the BCB president Nazmul Hassan, but many of the points he made were the result of pent-up frustration. He also acknowledged that he couldn't perhaps communicate well with the pace bowlers, which, by many accounts, is accurate.

Even though Bangladesh slightly misread the pitch in the first Test, Mushfiqur had hoped of at least a wicket or two in that first session. In that first Test, however, Taskin, Mustafizur and Shafiul conceded 58 runs off 67 balls marked as "short" or "full" by the ESPNcricinfo scoring team, which represented approximately 10% of all the balls they bowled in the Test. Against these two lengths, South Africa struck nine fours, one roughly every seven balls.

The three quicks only bowled two yorkers in 108 overs.

Nearly 70 per cent of their 648 deliveries were on a traditional good length, from which they picked up three wickets and conceded 452 runs at 3.05 per over. It showed that while they regained some consistency and control over their length in the second innings, they couldn't use the new or old ball well enough.

By contrast, Kagiso Rabada, Morne Morkel, Dane Olivier and Andile Phehlukwayo profited much more from that good length; They pitched 234 out of 492 balls on that length, taking eight of their 13 wickets there. That's roughly a wicket every 29 good-length balls. Compare that to Bangladesh's one in 150.

Since bowling short wasn't really an option on a pitch that didn't offer much bounce, the South African pacers refrained from overdoing it. They only delivered 49 short balls, picking up one wicket. Bangladesh bowled 25 short balls, getting one wicket.

Things grew worse for Bangladesh in Bloemfontein, where there was a bit more bounce but not much lateral movement. Mustafizur, Rubel and Subhashis ended up giving away 179 runs off the 165 short and full deliveries in the Test: which was more than a third of their total 456 deliveries.

The South African batsmen hit 31 fours off those short and full lengths, or nearly one four every five balls. But they were far quieter when the pace bowlers bowled a good length: 180 balls, 131 (or nearly 73%) dots. When they bowled a good length, Bangladesh's quicks only gave away 2.56 per over.

Here lies another problem that hasn't gone unnoticed: some of the pace bowlers strive too much for those magic wicket-taking balls. They don't aim to build pressure by bowling a succession of dot balls. Without much lateral movement, those wicket-taking attempts flip into bad balls.

In Bloemfontein, South Africa's pacers showed that, unlike their Bangladesh counterparts, they could use the short ball as a weapon: they pounded the batsmen with 157 short balls, taking five wickets while conceding 3.78 per over. On many occasions they got wickets with good-length and full balls while slipping them in amidst their short-ball barrage.

In Potchefstroom the Bangladesh pacers didn't show enough skills to use good-length balls to slow down the batsmen, while in Bloemfontein their short balls were too easy to handle.

Bangladesh also couldn't keep any of the South African batsmen on strike for a significant period of time. The starkest difference between the sides in the Test series lay in the singles conceded metric. The Bangladesh pacers conceded singles off nearly 20% of the totals balls bowled, while the figure for the South Africa pacers was just 8%. All other parameters (twos, threes and boundaries) were virtually the same for both sides.

Once they had done this poorly in the Tests, the prediction was that the problem would persist in the limited overs games. The steady progress of Bangladesh's quicks in the shorter formats since 2015 provided some hope that they would do better, but that quickly diminished when Mustafizur was ruled out of the ODIs with an ankle injury.

Nothing worked against Hashim Amla, Quinton de Kock, Faf du Plessis and AB de Villiers. What stood out instead was the lack of yorkers, which bowlers like Rubel Hossain and Taskin have been more inclined to bowl and better at bowling in the past. They bowled only three each in the first two ODIs and eight in the third game.

In all this, the role of Courtney Walsh comes to the fore. Over the last 13 months, most have found him to be a diligent and helpful bowling coach. He puts forth all plans and constantly offers the bowlers tips. He has gone out of his way to make the pace bowlers feel comfortable around him, often by bonding with them socially.

Some of the pace bowlers were not vocal enough when they were struggling, an observation that was especially true in New Zealand earlier this year. At the time it was seen as a minor and inevitable issue because Walsh was new, but while Walsh has since tried to overcome that, the bowlers haven't responded properly.

Walsh will, however, continue to have a greater role in their holistic improvement. Champaka Ramanayake, working currently for the BCB's High Performance Unit, will also have a role to play, especially because of his history with bowlers like Rubel and Shafiul. But the pair may have to enforce a tougher regime on the bowlers, starting with greater focus on bowling longer spells in the nets and taking it to first-class matches.

Will the BCB enable this? The answer is not quite straightforward.

As soon as they return from South Africa, the bowlers will become busy with the BPL. And tired bodies will be reluctant to play any first-class matches after December 12, when they are available to do so.

Sri Lanka arrive in mid-January, four weeks after the BPL. That is not really enough time to implement a cultural shift in how Bangladesh's pace bowlers develop, or even make necessary technical tweaks.

While there is a lot of dread flying around the Shere Bangla National Stadium, the good news is that everyone is worried, and thinking hard about how to improve things. This is a positive step and as a senior figure mentioned. "The South Africa tour was a disaster but it is good that it happened," he said. "If we forget about the South Africa series, it will be a disaster for Bangladesh cricket."