That is according to former Arsenal defender-turned-pundit Martin Keown.
Rudiger, 24, signed for Chelsea from Roma for around £34million this summer having been heavily linked with a move to the Premier League.
He has featured in six of the Blues’ opening seven league games so far this season, helping them earn 13 points as they sit fourth in the table.
Chelsea could have moved up to as high as second with a win over title rivals Manchester City last night.
But they were outclassed by Pep Guardiola’s side as they succumbed to a 1-0 win at Stamford Bridge thanks to Kevin De Bruyne’s second-half strike.
And during the match whilst commentating for BT Sport, Keown picked out Rudiger for criticism.
Ten minutes into the second half, Keown explained: “He doesn’t look, Rudiger, like he’s at the level required here.
“He looks very nervy in possession.”
Keown’s comment came as a result of City’s high-press tactics which forced Chelsea’s backline to move the ball on quickly.
Rudiger did put his defensive capabilities to good use towards the end of the game though, heading Gabriel Jesus’ goal-bound volley off the line.
Chelsea will be looking to bounce back from their loss to City when they visit Crystal Palace on Saturday October 14.