Root's Ashes conversion issues continue

Joe Root's inability to convert a solid half-century into a brilliant ton continues to haunt the England captain at the MCG on day three of the Boxing Day Test.

Root squandered yet another good start when he skied a simple catch to Nathan Lyon on 61 after he mistimed a pull shot off the bowling of Pat Cummins.

The furious skipper started walking off as soon as he sent the ball skywards, looking back only briefly to witness Lyon complete the regulation catch.

He kicked the ground and threw his batting gloves over the boundary rope in disgust.

His displeasure would have abated as the day progressed and double-centurion Alastair Cook helped his side to an imposing 164-run lead, but it remains an issue he must address.

In seven innings in Australia this summer, the 26-year-old has scored 15, 51, 9, 67, 20, 14 and 61.

Across his career, when Root makes 50 he only goes on to make a century 27 per cent of the time, which is the lowest conversion rate of all current top-10 Test batsmen.

"I know I'm a good player," Root said after the Adelaide Test.

"I know I'm going to score some runs out here."

While Root hasn't been in bad touch, his form doesn't stack up well against Australian counterpart Steve Smith, who is the series' leading run-getter with 502 and has hit two centuries, including a career-high 239.

CONVERSION RATE OF FIFTIES TO HUNDREDS OF CURRENT TOP-FIVE TEST BATSMEN:

1. Steve Smith (Aus) - 50 per cent

2. Virat Kohli (Ind) - 57 per cent

3. Cheteshwar Pujara (Ind) - 47 per cent

4. Kane Williamson (NZL) - 40 per cent

5. Joe Root (Eng) - 27 per cent