That's what happened Son vs Everton. Got sent off for the tackle, which ended very badly, but his red got appealed. So by that definition, it's a yellow. But I agree.It should be.
No intent for ball. Fine - stopping a breakaway is common and earns a yellow card. BUT:
The swinging leg and force is what makes it serious foul play. Merino's not just trying to stop a counter - he's swinging his leg to inflict pain. No need. Cynical. And Dangerous.
