The 20-year-old was named man-of-the-match in Tuesday’s 3-0 replay defeat and also acquitted himself well against Championship opposition in the original tie.
Ruffels has been the big success of United’s new development side this season and could keep his place in the XI for tomorrow’s home game against Torquay United.
The midfielder’s nine starts for the first-team are more than the rest of the squad’s youngsters put together.
He is delighted with a return of 17 appearances so far this season and thinks it means he has now graduated from the under-21 group.
“I wasn’t expecting to have made this many appearances at this stage,” he said.
“It’s been really good for me and I’ve gained a lot of experience. Hopefully, I can keep playing more as the season goes on.
“I feel like I’ve moved on from the development stage and I just want to stay in the first-team and stamp my place in the side and try to push for a place in the line-up.”
Ruffels, from Kidlington, was in United’s youth set-up before joining Coventry City.
He made two substitute appearances for the Sky Blues, but is in no doubt the extra playing time at United since rejoining last summer has been more beneficial.
He said: “I just played a few minutes here and there.
“It’s not the same as here, where I’ve started a few games and it’s been so much better.”
Chris Wilder admitted the midfielder was pushing hard for the place in the side held by Danny Rose this season.
He said: “I thought he led the way (against Charlton) and showed a lot of players how to do it.
“It’s only Danny’s form that has kept Josh out of the side.
“He’s possibly one of the only ones who is really putting pressure on the players in the team. We need a bit more of that.”