Hadden's men ruined England's Grand Slam dream and blew the Six Nations Championship wide open with a display of ultra-determined defence and admirable organisation at Murrayfield.
Scotland's first Calcutta Cup victory since 2000 came on the back of a stunning triumph over pre-tournament favourites France and a terrific effort with 14 men against last year's champions Wales in Cardiff.
It is a remarkable turnaround from the 2005 campaign under Matt Williams when victory over Italy in Edinburgh was all Scotland had to show for their efforts.
Now, they find themselves sitting joint top of the championship and with arguably their easiest two fixtures still to play.
Blair, though, believes the revitalisation of the Scotland team is only part finished.
The Edinburgh star said: "We had a really strong defence against England and got up in their faces to make them make mistakes.
"It was a great effort - but there are still things to come from an attacking point of view. We know we can play better in that regard.
"We hardly had any possession - it was mainly a rearguard action and plenty of defence. We just had to keep clearing our lines.
"We probably played more rugby against France and even against Wales with 14 men - but we've got to be happy with the result.
"We've got to realise where we are. Last year we only won the one game against Italy at home and we didn't have the support of the crowd. Rugby was struggling in the country as a whole."
Scotland travel to Ireland in the Six Nations on March 11, and the 24-year-old reports they will arrive in Dublin full of confidence and with plenty of belief.
Again, it is a huge change from 12 months ago when Eddie O'Sullivan's side - and particularly their forwards - steamrollered Williams' dispirited outfit at Murrayfield.
Blair said: "We've obviously got a lot of confidence now, and the mental side of international rugby is about confidence. We'll go into the Ireland game feeling good about ourselves.
"Ireland away is an incredibly tough game, but we've just got to stick in and do the things that we have been doing well so far.
"That's a big part of what Frank has brought to the set-up - and (captain) Jason White too. He has really bought into that aspect, as have the rest of the team really.
"Frank told us before the England game that we can compete with them; it's just about what performance we put in on the day.
"Fortunately we produced a performance. We defended very well, and I thought we deserved the win."