Mustafizur Rahman is slowly getting back to his rhythm and Bangladesh's assistant coach Richard Halsall explains that as the left-armer gets quicker, it will give more potency to his slower cutters.

Mustafizur Rahman's 2017 had not been his best as he failed to impress in the ICC Champions Trophy and was ruled out of the South Africa ODI series due to an ankle injury.

The cutter master seems to be slowly getting back to his groove and the left-armer capped a brilliant bowling performance with two wickets against Zimbabwe in the Tigers' opening match of the tri-nation series.

Fizz conceded only 29 runs and bowled 40 dot balls across his 10 overs as he bamboozled the Zimbabwe batsmen with his trademark cutters.

Bangladesh's assistant coach Richard Halsall informed that Fizz's pace is going up every week or so as he continues to recover from the shoulder injury he suffered back in 2016. The left-armer eventually had to undergo surgery on August 11, 2016. Halsall brought up an example from a sport that is alien to people in this part of the world.

"I think you have seen Mustafizur after his shoulder injury and if you look at elite baseball, lots of their pitchers had a similar injury. Now they have pitchers who pitch at 90 miles per hour. It takes them round about two years before they are back up to 90 miles per hour. I think Mustafizur is what 18 months since his injury and [against Zimbabwe] he used that cutter and his pace is beginning to creep back up to 85 miles an hour."

Halsall explained that the difference in pace between Mustafizur's cutters and his quickest ball will make his cutters more effective. 

"His cutter is still as brilliant as ever but his top end speed is beginning to go every couple of weeks -- another mile an hour, another mile an hour -- and the difference between his cutter and his quicker ball will be, instead of like this [gestured with hand to show small margin], it will be like that [a bigger margin].

"It makes the cutter more effective."

Since returning from injury Mustafizur had failed to make the same impact in 2017 that he had made during his debut year. In fact, there is a marked contrast between his 2017 bowling average and strike rate compared to his overall career bowling average and strike rate.

The cutter master's overall career bowling average is 19.56, with a strike rate of 24.5. However, in 2017, when he featured in eight ODIs, Fizz's bowling average is 35.62 with a strike rate of 42.7.

The stats tell the story of a fast bowler who has not found consistency in the last year. However, Mustafizur's superb spells against Zimbabwe, when he finally looked like he was regaining his rhythm, should give him the necessary confidence.

Halsall believes that Mustafizur's dedication to his art is paying dividends.

"I think his confidence is coming back and what's great to see is how hard he is working. If you see him at the net sessions, he is constantly working on his skill. To see someone who is in love with his passion, his skill, it's fantastic for everyone to see," Halsall enthused regarding Mustafizur's passion for bowling.

Mustafizur's cutters, which earned him the nickname of 'cutter master', is all about feeding the batsman with certainties -- in this case the pace of the delivery, followed by the uncertainty of the slowness of the delivery (bowled with a cross seam). It leads to batsmen playing their shots early, looking utterly baffled as they completely misread the pace (or rather the slowness) of the delivery. The trick behind this difficult art lies in the fact that Fizz was able to master bowling his cutters with a regular action, which makes it difficult to read for the batsmen when it comes out of the hand.

In 2017, during the ICC Champions Trophy, Fizz had struggled to hit the right areas. Former Bangladesh assistant coach Sarwar Imran had previously pointed out that Mustafizur was bowling from closer to the stumps back in 2015 but he was bowling from wide of the crease in 2017. That led to his cutters losing their effectiveness and also meant that batsmen were more certain of playing their shots against him.

Against Zimbabwe, Fizz appeared to be bowling from a tad closer to the stumps than he was during the ICC Champions Trophy and that would help him to control his pace as it creeps back towards the 85mph hour mark. At one point during the match with Zimbabwe, Mustafizur was bowling with three slips and two gullies -- a fantastic sight for cricket fans in Bangladesh. He is bowling with a much straighter action, having previously tried the round-arm approach without much satisfaction and it led to skipper Mashrafe Bin Mortaza showing his confidence in the bowler with that particular field setting.

If Halsall's words are right and Fizz's pace keeps increasing, thus rendering his slower balls more deadly, there will be many more occasions where Bangladesh appear as aggressive as they did against Zimbabwe.