Chelsea are tenth in the Premier League with 31 points after 22 games, the exact same position they were in under Graham Potter at the same stage last season.
The Argentine will hope to beat Wolves on Sunday afternoon to get things back on track, after a 4-1 defeat away at table-toppers Liverpool in midweek.
Mudryk, meanwhile, has dropped down the pecking order in wide positions, having joined Chelsea for £88.5million.
Asked why the Ukrainian is increasingly being overlooked, Pochettino said: "He started the game against Middlesbrough in the semi-final, which is one of the most important games for us.
"Yes, now he is on the bench. Look, it’s about the form during the season – if you keep your form and you are the best during every training session. As coaching staff, we are a meritocracy – we are going to play with the players who are going to do their best on the pitch.
"I think he’s a young guy that arrived here one year ago. We know the circumstances around [the transfer]. Of course, he needs to improve. He has amazing quality and potential, but it’s a [team] game, it’s not tennis.
"We have players that need to perform in a group. If you see him, it’s amazing, but after, you need to adapt and play for the team – he needs to adapt, and all of that needs time."
The Chelsea boss also explained why he believes his team cannot be compared with the side of last season, with a whole host of new players having joined the squad.
"Last season, I wasn’t here," he said. "It’s 15 or 16 players that are different from last season. How can you compare?"
"If you compare with this cup and another cup, that is completely different, so how can you compare?" Pochettino said while pointing to two different water bottles on the table. "If you had the same cups, maybe you can compare, but last season was another season.
"You have plenty of [different players] starting with the two keepers that won the Champions League, Kepa and [Edouard] Mendy were here last season and now we have two keepers that are young and came from different clubs, one who didn’t play at Brighton in the last few months and another is from MLS.
"Only you [people on the outside] can put it into context – you cannot ask me to compare this season with last season, whether it means today we are not in the position we should be or last season they didn’t perform – the players who three years ago won the Champions League."
On what is preventing such an expensively assembled squad from clicking, he added: "We have to stop using this excuse about the money.
"We are building a team for the future, of course, we are investing in players that for us we believe that they’re going to be for the next years to reach the level we expect.
"At the moment, we need to put it all in context, we need to put it all together, to build a team it’s not a magic touch.
"When you build a team with 16 or 17 new players, you need to all ask yourselves to look at all the circumstances from the beginning because it is easy to say 'oh we spent money or we have amazing names'.
"Is Nkunku performing after seven months in the way that we want? No, why? Because we we are not so good at managing players? [no] It is because of the circumstances, but I am so calm and relaxed."