Manchester's footballing giants met on Sunday during the 199th edition of the Manchester derby, in which the blue side reigned victorious and celebrated over their counterparts on Old Trafford's turf.

The two teams have been on very polarizing journeys in recent years. Manchester City have been challenging for previous Premier League titles and have a total net spend of roughly £400 million across two seasons; meanwhile, Manchester United have been battling debt and even relegation, surviving the worst period in the club's modern history.

The derby was plagued by controversial refereeing decisions. Phil Foden saw an early exit from the match after he retaliated against a battling Bruno Fernandes by kicking him in the stomach, and Pro Ref apologised just three hours after the match concluded, after overturning an offside decision that led to the only goal of the game.

United fans are left wondering what exactly is going wrong at the club. Michael Carrick's permanent appointment seems to have commenced with an underwhelming start, especially after the Reds were the most in-form side in the league in the second half of last season. So what's the cause of this dip in form?

The Old Trafford faithful were optimistic heading into the summer transfer window; reports suggested the Reds had upwards of £200 million at their disposal and had all but announced the signing of Atalanta's Ederson before his transfer collapsed.

With many top talents on the market, such as Sandro Tonali and Mateus Fernandes, United were expected to have a busy transfer window, and this was partly true: three new Premier League-proven midfielders were signed to bolster a position in desperate need of reinforcement.

But it seems Christopher Vivell and his recruitment team have put all of their eggs in one basket, as it's become obvious that the other areas of the pitch, such as left back and striker, also need strengthening.

Laurie Whitwell for The Athletic noted that United called upon Dutchman Joshua Zirkzee to rescue a point against City, a player the board had been attempting to sell by all means necessary this summer.

In contrast, Enzo Maresca turned to newly acquired talisman Illiman Ndiaye at half-time, who played a key part during the build-up to Erling Haaland's goal.

Zirkzee looked up to scratch during his cameo against Sabah FK on Thursday, but with nine goals in 77 games for the Reds, it could be argued that  Zirkzee was not the ideal man to call upon, especially in a Manchester derby.

Patrick Dorgu looked out of his depth at left-back, but he was chosen to replace Luke Shaw, who has been relied upon solely over the last few seasons. Dorgu struggled to manage Ndiaye in the second half and was largely at fault for City's winner.

It was obvious heading into the summer that United were in desperate need of a decent left-back alternative to Shaw, who can't be expected to play every single game for the Reds as he did last season.

With the left back area, as with a striker, United failed to pull the trigger on summer reinforcements, whether that be through being priced out of moves or abstaining from chasing the available players, but the options Carrick was left with in these areas led to United's demise in the derby.

The opening four games of the Premier League have been substandard, especially considering the expectations set at the start of the season. United have just four points from four games and have played two newly promoted sides, but it's the tactical inadequacy that leaves a lot to be desired for Carrick.

The Reds now have two games this week before the timely international break: a trip to Craven Cottage to face Fulham on Sunday, after a League Cup tie against Brighton on Wednesday, a side that scored five in their last match.

Without a doubt, and with names like Amad, Mathijis de Ligt, and Carlos Baleba remaining injured, the same side that hosted City on Sunday is likely to be picked for both games, despite their poor form.

Dorgu's physicality is usually his strong point, but he looked drained of energy against City, so Carrick may call upon Noussair Mazraoui to fill in at left back in either of the two games this week; he looked good against Sabah and was strong in the final third.

Zirkzee could get a chance in the League Cup, but fans will be calling for Benjamin Šeško, who hasn't started a league game this season but has been terrific off the bench and in the Sabah game.

Looking forward, it's obvious recruitment is needed during the January transfer window. But with top target Lewis Hall signing a new contract with Newcastle, and clubs reluctant to sell players midway through a campaign, it may be difficult for Vivell to stop this shoddy recruitment trend.