Ashton said: "We are very, very disappointed with the performance. That's not just me, that's my coaches and the 22 players in the dressing room too.
"I think we were outplayed. The best side won - there is no doubt about that. Full credit to Scotland for the effort on the day.
"It's frustrating because the area which we targeted before the game I felt let us down again this week. It's been mentioned before and I think it cost us the game today - discipline.
"It's not only discipline in terms of giving away penalties in kickable areas, although our penalty count was twice as high as Scotland's.
"The penalties gave Scotland the chance to a) get a stranglehold on the scoreboard, b) to gain territory without having to work for it and c) also stopped us from getting any continuity of play.
"It put us on the back foot from that point of view but it also stopped us from enabling ourselves to carry out individual execution.
"Scotland probably tactically won a part of the game that we thought we would be better in - and I mean the kicking - although I'm not pointing the finger at anybody in particular, it's about collective responsibility for the whole team.
"If you put all those things together under the heading of discipline, if we would have won today, I might start to believe in miracles."
Despite England's lack of cutting edge, Ashton was adamant his decision to withdraw Danny Cipriani from the side for disciplinary reasons was the correct one.
Cipriani had been an electric presence in training but Ashton stood by his move and insisted England never produced a platform from which to attack.
He said: "Our defence in training, with all due respect to Mike Ford (defence coach), is not as physical as Scotland's was today.
"I explained why I left him (Cipriani) out during the week and I'm not going to go through that again.
"I was yearning for anyone to open the door but we never got in a situation to be able to do that."