It makes all the difference in the world if you're defending the lead with 10 minutes to go. It's literally the one thing that's useful about experience, you can handle situations easier if you already experienced it.
Yeah, one has actually played professional football for a couple of years, the other one hasn't. How is there no difference?
Teams drop back all the time, you're arguing we wouldn't because we barely managed to pin them back for all of seven minutes. It just takes a bit of possession for Sheffield and we would have been exposed with our none existent midfield.
They weren't going to get that possession though. They have lost their legs and were collapsing. They couldn't do anything against Fred and Lingard midfield anyway because of that, they ran out of steam completely. More pressure and we would have scored even one more I reckon. By that sub we actually gave them a chance to regroup, gather themselves, regain possession and start making few attempts. We brought them into the game. They were on the verge of losing it.
I honestly don't care at all about this experience thing. I'll prefer putting an inexperienced player in his right position at the right moment than put an experienced player in a wrong position at wrong timing. The first one has a bigger chance to succeed.