The 35-year-old keeper made his Boro debut in Saturday's 2-0 FA Cup third-round defeat by Hull with loan signing Shay Given ineligible as a run of five games in 15 days drew to a close.
However, the Teessiders had taken 10 points from a possible 12 in the four Sky Bet Championship fixtures which preceded it to leave themselves within striking distance of the top six.
Konstantopoulos told the club's official website: "Saturday's game was at the end of two weeks of five hard games.
"The FA Cup is a great competition, everyone wants to play in it. I'm sure those from other clubs who said they don't like it have their reasons.
"Now it's the league for us. We are six points off the play-offs, and that shows how far we have come since the gaffer came in. We are picking up points, playing well and getting results."