Apart from the whole thing being way off topic. LMS was injured and so one of Walker and Greenwood had to play. Also Amor was injured during the match, reducing his impact meaning there was more needed from the young lads.
The question about Laffranchi is one that can be asked, but that's 100% easy using hindsight. There is also the question about whether Walker and Greenwood earned their spot against Leeds. As you say the coaching staff know best and if they are saying players earn the spot until injured or until they lose it then it's no good putting players in the side based on a name alone.
Walker and Greenwood earned their call up from the Leeds game, as did Lance over Wheeler, As did Wellens. You can't unwrap all that saying they all play well against Leeds yet one should be kept one should be dropped. Given the performance I would had replaced Lance with Wheeler, but I would not have said it pre match as Lance earned the shirt from his previous performance.
There is a lot of duplicity on this thread using one theory to pick one player, but a different rule to drop another.