Spence doesn't play every week to make those mistakes every week and most of the time he does play he isn't playing at right back so with respect you're just making stuff up.
I've shown you the freeze frames in much more detail than those two you've posted. You can see where Howson decides to pick up Rothwell but then leaves him, just as he decided to pick up Armstrong and then left him as well. So he left two players, still ended up in a position to clear the ball as our last man but stood still instead. That's not me absolving Spence of blame because he still switches off like I said. It's just that he clearly isn't the only one who has done this but he is the one getting the grief for it.
I mentioned "Leadership" in my reply to Leesider earlier, there wasn't much of it in evidence. Warnock has created a problem in giving the armband to Britt. It hasn't improved his game and he isn't a Leader. That's not Britt's fault but the lack of a Grant style Leader when they scored was an abject embarrassment.
He didn't leave his man on the left side. That wasn't his man, that's my point. Rothwell actually was his man, which is why he does drift across the pitch. Spence's mistake was switching off but he was in the 'right' place, based on how we seem to want to defend, which seems to be that every player has a specific opposition player they are supposed to follow.
Howson is marking nobody at all because he leaves Armstrong, who isn't his man in the first place, and he is also the only player in position to clear the ball, but he stops moving and stands still even when the opposition have gotten goal side of him. You can't play anyone offside in that situation so what are you doing standing still when you know you're the last man back? That is terrible play from a player who has enough experience to realise what is happening. He does it time and time again, he did it when he was playing as a defender for us as well.