The latest talented No 10 off the Ponty production line had already kicked a penalty, created a try for Jack Pope and added two conversions before he was forced to leave the field in considerable pain near the end of the first half and was taken to hospital.
While he was on the field the visitors looked capable of matching Merthyr, but once he departed it became one-way traffic.
When he ghosted through the home defence to set up Pope for his try at the posts, the conversion edged Ponty into a 17-14 lead.
There was still only a point in it at the break, the Ironmen leading 21-20, but the second half brought six more tries for Craig Locke and his team as they cruised to morale boosting win.
“We put pressure on to the end, although they lost a bit of control and direction when Ben went off. That enabled us to play in the right areas of the pitch,” said Merthyr head coach Dale McIntosh.
“The backs were very good, which was pleasing, but our line out drive and scrummaging in the first half wasn’t as impactful as it has been.
“We have still got a lot of work to do and we’re doing things the hard way at the moment with 14 players out with injury and COVID elated problems.
“I know the west Wales league is strong, and Cardiff are tough to beat when they put their big boys out, but we are building nicely towards the start of the league campaign.”
The game had all the hallmarks of being an even contest before kick-off with only a point splitting the two teams in the Indigo Premiership Cup table. This runaway victory edged Merthyr three points clear of Ponty in third place.
A highly competitive first half saw Burnell kick the visitors ahead before tries from Callum Bradbury and Gareth Thompson made it 14-3. Man of the match Thompson would go on to score 17 points, yet there was only a point in it at the break with the home side leading 21-20.
Then came the second half barrage with inspirational skipper Craig Locke bringing up the bonus-point with the first of the half-dozen in the second half. Ponty at least left with a bonus point thanks to a last gasp try from Cai James.
Merthyr face top of the table Newport at The Wern in their next game, while Ponty host second placed Cardiff. Both games kick-off at 1.00pm on Saturday, 20 December.
