The performances are only worrying if you dont put any context around them and only look at the balance sheet.
Since the Dundee United game you highlighted we have played the following in the league......
Hearts (H) 0-3 - vibrant attacking performance, created a bucketload of chances and got picked off on the break. Hit the woodwork 3 times and Craig Gordon pulled off numerous saves. Should have won the game. Got mugged.
Celtic (A) 1-2 - gave a good account of ourselves at a difficult venue against a very good Celtic side. Unlucky not to nick a point.
Ross County (A) 0-5 - tight first half with little quality on show by either side. Dominated the 2nd half played some good football and scored 5.
Hibs (A) 1-0 - tight game at another difficult venue against a side with far superior resources. Denied a stone wall penalty which VAR would have given and continued to threaten even at 1-0 and a man down.
Rangers (H) 1-2 - Another tight game against opposition with far greater resources. Well in the game first half before we shot ourselves in the foot twice before regrouping and getting a goal back. Rangers hanging on at the end. Poor quality in final third prevents us ffom getting anything from the game.
Aberdeen (H) 1-2 - Another tight game against opposition with far superior resources ( you might see a pattern here). Poorest first half performance out of all the above. Changes made at the break, dominate 2nd half, score a good goal then shoot ourselves in the foot again before continuing to press for an equaliser. Denied a stone wall penalty and VAR inexplicably fails to intervene.
Im happy to accept our performance levels have dropped off in the last few games, but if you look at the opposition, our injuries and suspensions, there are more than enough mitigating factors.