"Bulu, did you see who's inside?"

"There was the foreign coach, and another guy wearing t-shirt. Who is he?" Bulu asked breathlessly and then walked away briskly, as usual.

Bulu is a tea-maker for cricket stars. He has souvenirs from Sachin Tendulkar and MS Dhoni. He once advised Tamim Iqbal on his form. But he couldn't recognise Mustafizur Rahman sitting in the physio's room at the National Cricket Academy in Mirpur.

Bulu's official duty is to help take care of the media. Only minutes had passed before he returned with a bottle of water for the journalists waiting outside. "How come there are so many cameras here?" he asked softly.

It was only when Mustafizur came out of the room, and feigned running away from the cameras, that Bulu recognised who he was.

*****

Mustafizur's IPL campaign - 17 wickets at 24.76 - went as his Bangladesh captain Mashrafe Mortaza had predicted. Perhaps even better, considering the 20-year old left-arm quick and his team Sunrisers Hyderabad emerged champions.

"I said it in interviews before the IPL, even as far back as November last year, that he [Mustafizur] would trouble all the batsmen in the world," Mashrafe told ESPNcricinfo. "From the way he troubled top international batsmen in 2015, I knew that those in the IPL would have a tough time taking him on. And as you have seen, it wasn't easy for anyone.

"From what I have seen of him in the tournament, Mustafizur has used the yorker quite well. It came in handy for him to keep the run-rate down. Batsmen know that he is all about the cutter, which makes them think of him differently. So he has improved a lot, and with more experience he will do better."

Mustafizur's economy rate of 6.90 was the best in the IPL, under condition of 120 balls bowled. He was named the Emerging Player of the Season, but he was already a vital cog for Bangladesh in limited-overs cricket, having helped them to series wins over India, South Africa and Zimbabwe in 2015.

*****

Mustafizur has never spoken about what kind of ball he prefers - red or white, new or old. He has opened the bowling in all of his 14 first-class matches and nine ODIs but the bulk of his wickets have come in late spells.

Considering only three days' cricket were possible in his debut Test series, Mustafizur could bowl no more than 22.4 overs across two innings. Three of his four wickets - Hashim Amla, JP Duminy and Quinton de Kock - came with the old ball.

Similarly in ODIs, 18 of his 26 wickets have come after he has bowled five overs in a match. His captains - Mashrafe and Mushfiqur Rahim for Bangladesh, Kumar Sangakkara for Dhaka Dynamites in the BPL, and David Warner in the IPL - preferred to use him in the slog overs.

Mustafizur is expected to be critical to Bangladesh's ODI plans, especially in the 2017 Champions Trophy, and for ensuring automatic qualification for the 2019 World Cup. So it won't be surprising if he is given time off from Test cricket.

*****

Mustafizur is contracted to play limited-overs cricket for Sussex in the English county season. The BCB hasn't decided when they will send Mustafizur, and the man himself is not keen on another stint outside his beloved Tetulia village in southwest Bangladesh.

Coaches and former cricketers believe he should go to UK because playing in different environments would help him grow as a player. The Bangladesh management, however, is worried about overexposure.

Participating in domestic tournaments around the world could lead to batsmen figuring out the mystery of his cutters, and possibly result in him becoming a diminished force for his country. In the IPL final, Virat Kohli was able to take him on by stepping out of his crease or making room to the leg side. But Mustafizur is said to have a beautiful cricketing brain and he is a tremendous competitor. As he showed in the IPL, his yorkers beat batsmen who may have thought the only threat he posed was with the slower ball.

Mustafizur has generated a lot of interest in Bangladesh, and around the world. Shakib Al Hasan and Mohammad Ashraful had done the same during their careers, and at times had been handled poorly. It is important that the team management and the BCB do better considering Mustafizur's temperament. He is still a shy, small-town boy and he will need help handling off-field issues.

Mustafizur is a rare bowler. Fitness and form withstanding, he will stoke the club v country debate regularly in the coming years. He will need to be guided properly, given the right signals, and then the freedom to express himself.

Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84