Cristiano Ronaldo has had a topsy-turvy time since rejoining Manchester United in the summer.

The 36-year-old returned under former team-mate Ole Gunnar Solskjaer and now plays for Ralf Rangnick, who he was mightily frustrated with when taken off at Brentford on Wednesday night.

The interim boss publicly defused the issue after United’s 3-1 win in the capital, where Ronaldo returned after missing two matches with a hip flexor complaint.

The Portuguese has seen some ups and downs since returning and here the PA news agency looks at his 20 weeks back at Old Trafford.

What has Ronaldo’s impact been since returning to the club?

Having been tipped to make a controversial switch from Juventus to rivals Manchester City, the 36-year-old instead returned to the club he left in 2009 returned for an initial £12.86million in August. Ronaldo made his second debut for the club in front of a packed, expectant Old Trafford on September 11 and did not disappoint, scoring twice in a thumping 4-1 victory against Newcastle. The forward would score in four of his first five United games and has managed 14 goals in 22 in all competitions so far. As well as scoring an average of 0.70 goals per 90 minutes, he has provided three assists.

What did he walk into?

United have stuttered since Sir Alex Ferguson’s retirement in 2013, with the despised Glazer family’s ownership providing a challenging backdrop. The club appeared to be on the right track on the field last season as Solskjaer oversaw progress, finishing second in the Premier League before losing an agonising penalty shootout in the Europa League final. The summer arrivals of Ronaldo, Jadon Sancho and Raphael Varane heightened hope and expectation, but things unravelled this term as chastening losses against Liverpool and City helped send United into a tailspin. The humiliating 4-1 loss at embattled Watford in November led to Solskjaer’s exit and, while United have only lost once since then, performances continue to underwhelm.

Has Ronaldo been an ineffective signing?

Some have suggested Ronaldo has had a big part to play in United’s struggles, but that would be foolish. Without him the club would almost certainly be out of the Champions League, plus the forward boasts twice as many goals as the club’s next highest scorer. It is, though, interesting to note that United have a better Premier League goalscoring record without Ronaldo than with him (2.05 goals per 90 minutes compared to 1.33 without). The Red Devils also concede fewer goals without him in the side (0.79 per 90 minutes compared to 1.52 with him). The level of opposition needs taking into account, so too the context of overall play of team-mates, but there is little doubt he can be used more effectively.

What next for Ronaldo and United?

Ronaldo, who turns 37 next month, is a standard-bearer at United. He may not wear the captain’s armband but last week he spoke with authority about the need for an improved mentality at a club where he won numerous trophies during his first stint. With the Premier League beyond United, Ronaldo is targeting a top three finish in a season where the Champions League and FA Cup offers their only remaining routes to silverware. If they are to get anywhere near achieving those ambitions then Rangnick needs his side to show more coherency, control and quality. Utilising Ronaldo’s elite skillset while adapting to his abilities will be key to that. Moving from the much-discussed 4-2-2-2 system to a 4-3-3 has shown Rangnick’s willingness to adapt, but a wretched first-half performance at Brentford highlighted that work is still required. A stronger understanding also needs building with Ronaldo if the reaction to his substitution is anything to go by, but a man with more than 800 professional goals to his name will give United the chance to kick on.