Mahbub Ali Zaki was filled with pride as he watched Taskin Ahmed bowl in the third ODI against Afghanistan. He was comforted by how the fast bowler, playing his first international series since his bowling action was cleared by the ICC, was ticking through his check-list smoothly, and looked prepared for bigger battles in the coming weeks.

"I am really proud of him," Zaki says, four days after Taskin finished as the joint highest wicket-taker in the ODI series. "I helped a guy who was facing a major threat in his international career come back to where he belongs, after correcting his suspect bowling action. He was delivering the bouncer and yorker at high speed.

"I think we didn't have to make too many changes to his action but certainly he looked like a refreshed bowler. I didn't see any speedgun in the Afghanistan series but Taskin later told me that he felt that he was bowling at his old speeds."

The 50-year old Zaki is a former fast bowler who is now employed by the BCB as a specialist bowling coach. In April this year he was asked by Heath Streak, Bangladesh's bowling coach at the time, to record videos of Taskin's action while Streak was away with the IPL side Gujarat Lions. After Streak quit the Bangladesh job, Taskin's rehabilitation had to be monitored solely by Zaki.

Here was Bangladesh's most promising fast bowler since Mashrafe Mortaza and Talha Jubair, and it was up to little-known Zaki to get him ready for his second independent assessment. Zaki now says he knew that Taskin was a special bowler who needed to be dealt with differently.

"I quickly understood that I was dealing with a young fast bowler," he says. "If I took him as a general example among such bowlers then I would have to make lots of biomechanical changes to his action. Taskin the cricketer isn't the same without his pace and bounce, so we focused on keeping his pace while making those subtle adjustments to his action."

To the naked eye, there is hardly any discernible change to how he runs in and bowls.

The point where his action differs from most other fast bowlers is when he loads up, when he brings his arm up just as he lands on his back foot prior to his delivery stride. Here, his wrist points towards midwicket (to the right-hand batsman) rather than down the pitch.

Now, this unusual positioning of his wrist is possibly even more pronounced, but the rest of his action remains more or less what it was earlier. Footage confirms that Taskin's load-up remains consistent with how it was even as far back in 2012, when he bowled in the nets in front of Bangladesh coach Shane Jurgensen and Academy head Richard McInnes, or a few months later when he played his first BPL match, or even when he made his international debut two years later.

Coaches love a consistent bowling action, especially if it works for the bowler. Taskin was certainly one of Jurgensen's favourites, and he pushed for the fast bowler's debut during the 2014 World T20. After Jurgensen left the Bangladesh job, Taskin's ODI debut produced a five-wicket haul and he didn't look back, performing well until the 2016 World T20 when he was reported for a suspect action after Bangladesh's first match.

Since being reported in March, Taskin has undergone two independent bowling-action assessments in Chennai and Brisbane, the latter clearing him to bowl again in international cricket. The report obtained by ESPNcricinfo says that Taskin did not go past an average of five degrees, upon ball release, in an over at the Brisbane assessment. Out of the 24 deliveries he bowled, only four went up to seven degrees while some others touched six degrees.

Arafat Sunny, who was reported and suspended at the same time as Taskin, also underwent a reassessment in Brisbane. His highest average for ball release in an over was 11 degrees, and the lowest was six degrees.

If not among all current bowlers, Taskins's action is being regarded as technically one of the better bowling actions among bowlers who have been reported for suspect actions or suspended for illegal actions.

To get to this point, where the straightening of his elbow is well within the prescribed 15-degree limit, Taskin required minor changes to be ironed into his action. Zaki says keeping his pace intact was the major challenge. To record what he was doing, he used eight different camera angles to ensure everything was captured and he had the necessary data.

"It was certainly one of the most challenging projects of my coaching career," Zaki says. "I was trying to help a kid whose career was on the line. My initial target was to take him back to his old rhythm, which was to ensure that he bowls between 138 to 148kph. We couldn't afford to lose his pace.

"I recorded his action from eight angles in total and only after I was totally convinced from one of the angles did I move to the next one. The angles were the usual four TV camera angles and then I did some from 45 and 35 degrees. I also used a fire-service ladder to get an overhead shot of his action. I recorded him every week from mid-April to the end of August."

Next, Zaki installed large mirrors to provide Taskin a personal perspective whenever he had some downtime at the Shere Bangla National Stadium or at home.

"Inside the dressing room where the coaches often sit, I set up a nine-foot mirror for Taskin," Zaki says. "I did a similar thing in his home where I put up a 6x4 foot mirror so that he can try out his action in front of it. We tried the action thousands of times."

The work put in by Taskin has certainly been praised by those who saw him from April to August, when he also helped Abahani Limited to their 18th Dhaka Premier League title. But Zaki's efforts shouldn't go unnoticed.

Zaki replicated what Mohammad Salahuddin did with Abdur Razzak when he was suspended from December 1, 2008 to March 12, 2009. Salahuddin is regarded as one of the most technically sound coaches in Bangladesh. Now, given Zaki's success with Taskin, the BCB should use him regularly to spot defects in the actions of a number of bowlers in domestic cricket.

"My eyes have become experienced now with Taskin's action," Zaki says. "When he bowled towards the end of the third ODI against Afghanistan, I felt that he was at his best. His action didn't have any chinks whatsoever. It was a very fair action."

Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84