The newly promoted club have claimed 12 points from their opening 15 games and currently sit one point clear of the relegation zone.
Boro have picked up six points from their last five outings, winning just once, but showing they have plenty of resilience.
However, Karanka feels the good performances will count for little if they don’t start turning draws into wins.
Karanka said: “The players have shown they can cope with the Premier League. My frustration is how much it takes for us to add points. If you look at the table we have 12 points, but we should have won against Stoke, Arsenal and Watford.
“We should've at least drawn against Crystal Palace so we could have got 18 or 20 points. That's one side of my frustration, but the other side is that one day we will start to win the games and get more confident.”