5? You're talking about David Luiz.
Smalling penalties :
Borussia M - Penalty given against Smalling for "handball" but it hit him straight in the face. Clearly incorrect
https://www.bbc.co.uk/sport/football/50175001
Torino 2 - 0 Belotti shoots, Smalling blocks and then doesnt know where ball is and handballs in the box
Milan 2 - Roma 0 Smalling gives away a penalty sliding in, Calhanoglu converts
https://www.acmilan.com/en/match-center/g2021330/statistics
So one penalty for handball, one for a slide tackle and not getting the ball and one phantom penalty for the ball hitting his face
2 actual penalties conceded in 36 starts in all competitions. It is higher than he normally gives away but it is essentially one mistake with his hand and one bad tackle that gave away a penalty in 36 games.
Roma didnt have the luxury of a defense that was bought for over £190 million. Smalling didnt have £120 million of defenders signed to come into the side next to him this season.
In fact they had loads of injuries and players unavailable last season. When Roma did have a first choice defense it was Mancini - Smalling - Kolarov and Santon who played 7 games at RB and then injured, Florenzi who played 10 games at RB then on loan from christmas at Valencia and then 6 at right back from Spinazzola who also played 6 left back and 6 left wingback.
So Roma's first choice defense this season was bought/valued - Mancini £11.7 million to be paid this summer after his loan, Smalling Free on loan with a £20 million valuation if they want to keep him, Kolarov £4.5 million and Santon £8.5 million. Their first choice defense was assembled with £44.7 million even if we count Smalling by his value and Mancini even though they dont have to pay till this summer as he was on loan
Even if we throw in the players who filled in over the course of the season for Roma at fullback positions - Spinazzola £26.5 million (dud) and Bruno Peres £11.2 million on top of pretending Roma actually paid for Smalling or Mancini last season at full value, their defense would still come to £82 million. Not even close to the £127 million we paid for AWB and Maguire this summer alone, let alone the £190+ million we spent on AWB, Lindelof, Maguire and Shaw.
So yeah no shit he gave away 2 clear penalties and Roma conceded 51 goals (not all in matches he was playing) while United conceded 15 less goals. Smalling did even better 2 seasons ago and Phil Jones was his partner
Lindelof was essentially playing in Fort Knox, with a £55 million RB doing half his job to the right and a £78 million CB to his left doing a third of his job. And he still wasn't convincing.