The Leeds winger believes he isn't doing as well at club level as with Northern Ireland.
Dallas joined Uwe Rosler's Leeds side this summer and has generally impressed. But the winger feels he can play better and has been disappointed with himself throughout the Championship season to date.
As such, Dallas is keen on improving himself in training, with Rosler's men currently struggling for form in the league.
The 24-year-old is quoted as saying by the YEP: "For Northern Ireland I’ve done well. I think for Leeds, maybe my performances could be of a higher standard.
"I’m my biggest critic and I set the highest standards I can. Sometimes I’m disappointed when I come off the pitch but that’s the way it is. You keep working hard.
"I’ll always give 100 per cent. That’s a given. Any player who doesn’t shouldn’t be here. But there’s always something you can improve because nobody’s perfect. That’s why you train - to put things right."
Is the Leeds winger actually being rather harsh on himself, though?
Unfortunately for United, Sam Byram hasn't quite been the same so far this season, while a number of other first-team members have undoubtedly underperformed.
Dallas, however, has been one of Leeds' better performers, which is especially telling considering he only joined up with the Whites this summer.
The 24-year-old's attitude of wanting more and criticising himself is refreshing. It will only push him on further. And it would be good to see some of his Leeds team-mates take a similar approach.