Is county cricket's substitute rule working?

Former England wicketkeeper Sam Billings, who is currently playing in the Pakistan Super League, has been the most stinging in his criticism, calling the law "ridiculous".

Glamorgan's Carlson said his complaints were "no slight on Notts whatsoever".

Former England coach Moores said he expects the laws will be refined at the end of the season, agreeing that players coming into a match late is an issue.

"There will need to be some tweaks to make sure it is tight," Moores said.

"To have two in this game, we want to make sure that it doesn't become a focus for the season when we want it to be on the cricket.

"There is a case for a tightening what point in the game can it be done."

Kerr said: "If someone is genuinely injured and they can't do the job they are selected to do, it is a good thing.

"You could find ways to manipulate the system and use it to your advantage, and that does concern me. I won't be doing that."

Kerr said replacements for illness or soft issues injuries may need to be "tweaked".

"I can think of games last year where we didn't select players because their partner was expecting," he said.

"It means they missed the game and there were times the baby didn't arrive.

"If you can mitigate that and replace them, that looks like a win-win that is common sense - similar from a bereavement point of view."