Pakistan bowler Usman Tariq and his unusual delivery courts controversy at T20 World Cup

Usman Tariq's unconventional bowling style sparks controversy at the T20 World Cup, raising questions about legality and effectiveness.

With a momentary pause in his delivery and his statue-like pose at the crease, Pakistan spin bowler Usman Tariq has created plenty of attention at cricket's Twenty20 World Cup.

Just enough, it seems, to throw off opposing batters.

With it has come a fair share of controversy — that his pause-and sling style of bowling is an illegal delivery, or in cricket parlance, chucking. He's already been reported twice, but cleared, by Pakistani cricket authorities.

The 28-year-old offspinner's unconventional bowling action has already mesmerized some of the big names in shortest format of the game and has seen him taking three wickets against an inexperienced United States in Sri Lanka this week in what was his first T20 World Cup game.

As is often the case in cricket, the reasons for Tariq's potential illegal delivery are complicated.

First there is the so-called "15-degree debate" — that bowlers cannot exceed the ICC's 15-degree elbow flex limit, which is nearly impossible for on-field umpires to judge accurately in real time.