Chelsea reached the FA Cup quarter-finals after a victory over Wrexham in round 5. Although only facing a lower-ranked opponent, it took 120 minutes for Joao Pedro and his teammates to win a ticket to the next round, very hard and not easy at all.
The most noticeable thing about Chelsea under Liam Rosenior is their stable control ability. They may overwhelm the opponent for a large period of the match, but that's not all. The Blues almost didn't know how to finish the match when they had an advantage for most of the time with Rosenior.
Chelsea won 4-2 against Wrexham but for most of the match, they did not play perfectly. When the opponent had to play with 10 men, Chelsea still struggled in extra time to be able to seal the final score. It is difficult to use the reason of a reserve squad to defend because Chelsea's opponent is a club playing in the Championship.

The 4-1 victory before when facing Aston Villa could not make a good psychological baggage for Rosenior's team when traveling to Wrexham's stadium. There were many matches Chelsea was playing well but unexpectedly lost. Against Wrexham were Aston Villa, Wolves and Leeds, matches that could have been very easy to close, but The Blues were still negligent in many moments to let the opponent have a chance to reverse the score.
Liam Rosenior clearly recognized this problem. After the match against Wrexham, the English coach shared that everything seemed to be the same as 6 weeks before he came to take over the team to replace Enzo Maresca. Chelsea have played well in most matches since then, but there have also been countless matches where they don't know how to finish when they have an advantage.
4 points lost to Leeds and Burnley could be the ultimate regret if at the end of the season The Blues cannot win a Champions League ticket. If they had not lost those regrettable 4 points, the team ranked 3rd in the overall standings should have been Chelsea, not Man United.
During Liam Rosenior's reign, Chelsea lost 3 matches and the opponent was Arsenal. Except for knowing how to finish teams that are underestimated, The Blues also need to improve in terms of class to be ready to face big opponents. In the immediate future, it will be PSG in the Champions League round of 16, can The Blues repeat the achievement in the FIFA Club World Cup 2025 final?

From now until the end of the season, Chelsea still has 3 arenas and every stage has reached the final stretch. If these problems are not improved soon, from being expected to finish well with Liam Rosenior, The Blues may lose everything and have to rush into the vortex of rebuilding from scratch.