De Sa surprisingly traded Soweto giants Orlando Pirates for Ajax in February last year.
And the ex-Bafana Bafana goalkeeper has impressed in Parow, steering a young side to MTN8 honours on Saturday and to the top of the League table following a creditable fifth-placed finish last term.
"Credit should go to Roger," Efstathiou says.
"With the limited resources he has managed to bring the good results and promote lot of youngsters. This is part of our project and few coaches can do that.
"He believes in the players and the players believe in him. The results show that football is alive and kicking in Cape Town."
The Urban Warriors beat former Cup holders Kaizer Chiefs 1-0 in the Final on the weekend to claim their first piece of silverware since their 2008 Telkom Knockout triumph.
Efstathiou revealed that no bonuses were discussed before the game at Nelson Mandela Bay Stadium, but he says De Sa's charges will not be short-changed.
"The players knew that they have to play for this club and no money was discussed before the game. But obviously the players will be rewarded for their efforts and it's something that cannot be discussed in the media."
According to a source close to Ajax the players stand to share half of the R8 million prize money.