The ridiculous idiot Graham Polls explains:

When Matt Ritchie flew in with a high boot towards Alfie Mawson you could see he was clearly worried which colour of card Mike Jones would produce — no doubt after Sadio Mane's red card the day before.

The aerial challenge was incredibly similar apart from the contact on Mawson, who should be applauded for his calm reaction to the incident.

Jones showed a yellow card, which I think was because he thought there was no contact. Had he seen contact, which was made on the Swansea player's forearm, then a red card would have had to be shown as the challenge certainly endangered the safety of Mawson.
So dangerous play now relies upon contact being made? Or put another way, you can launch a two-footed, studs up drop kick at an opponent and if he dodges, yellow card because there's no contact. And using Poll logic, if you go for the ball and accidentally make contact, red card.

Makes perfect sense Graham. You idiot.