I think the goalkeeper and defense line both have shortcomings, in the sense that they still need a series of adaptations. This is Onana first season, and we know that most of Man United defenders have just returned from injury, ultimately causing United to concede in every game they play. It's true that Ten Hag must quickly find a solution for United XI formation, and I don't think there's any harm in giving time to young players, if the more senior players consistently make United performance plummet.
Exactly, if Ten Hag cannot bring United to consistently achieve points, the consequences will be very bad, he will not qualify for the last 16 of the UCL, and in the EPL his position will continue to sink, and will end his tenure at Old Trafford sooner.
Manchester United goals keeper and defender still bigger problem for Manchester United in this season, Andre Onana need more time for adapting well and he was conceded many goals 18 goals from 9 matches all competition between Premier League and UEFA Champion League. Unbelievable with Manchester United weakness defense due have conceded many goals last 9 matches all competition, need with new recruitment as central defender how to make Andre Onana more secure as goal keeper position due many critic show for him after conceded many goals in this season.
Manchester United opportunity qualifying to the next round not close yet, have get full points on left four matches in group stage if get chance finish on 2nd standings place and upcoming match against Copenhagen must get three points.