It wasn't for no reason, before he went to slide in him, Pogba or Lingard made a shocking error and lost a ball in the build up, so the counter needed to be stopped. In the end it was harsh from the ref as he pulled out and the burnley players acted like he got his legs broken, could be somehow justified from the ref as an attempt to stop the counter... second one was a nonsense very harsh for a second yellow, he slipped and if I remember correctly it wasn't in a dangerous area...
if anything that cnut Flanagan should have been sent of for a clear handball as a result of a second yellow card, the most refs would have give that after they harshly sent off a player for two minor tackles or even if Herrera wasn't sent off..
I can sense Clattenburg have an irrational dislike for Spanish players..