Simms had arrived on loan from Everton just two days before the start of the Championship season, and went straight into the matchday squad with the Black Cats lacking cover and competition for Ross Stewart.
Neil admitted he was tempted to hand 22-year-old a debut from the bench in the second half as Coventry City began to take greater control of the contest, conscious that it could change the rhythm of the game.
However he felt he couldn't lose a player from the crucial midfield battle, and noted that his side almost won the game but for a goal of superb individual quality from Viktor Gyokeres.
Manchester United ‘tipped’ to sign £20m Newcastle United star and striker sold by Rafa Benitez
Sheffield United missing NINE players - including Newcastle United loanee and ex-Leeds United striker
Supercomputer predicts final Championship table - including surprise finishes for Sunderland, Middlesbrough, QPR, Sheffield United and co
Ex-Sunderland youngster completes Scotland switch and divulges what Alex Neil told him prior to release
Sheffield United 2 Sunderland 1: Story of the night after Lynden Gooch goal and Dan Neil red card
Asked if that individual strike underlined the step up from League One football, Neil said: "Throughout any 90 minutes at this level, it's very rare that you're going to dominate from the first minute to the 90th.
"You're playing against too many good players, too many good coaches, and they will have moments in the game.
"I was tempted towards the end to put Ellis Simms up top with Ross Stewart to turn the ball a bit more, but I was just worried about that central area because we were starting to lose hold of that part of the pitch.
"Hence why I put Luke O'Nien in there, to try and have a bit of physicality and energy.
"At that point, we were winning the game and I didn't feel there was a need to take any more risks."
Neil was also full of praise for the way his players applied themselves defensively throughout, which will be crucial in a campaign where they are likely to see less of the ball than in League One.
He saw clear signs of encouragement even if he felt his XI could have looked after the ball better in the aftermath of their opening goal.
"People on the outside will say we should be up there but we've been a League One team for four seasons," Neil said.
"The lads understand that, when you speak to them, they want us to strengthen the squad, they want us to be nice and compact and hard to break down. Equally, we have got quality in the team.
"Some of our passing movements in the first half were excellent but you've also got to give Coventry credit, they're a good side with good players.
"I felt that if we left space in behind us, the likes of Gyokeres, O'Hare obviously didn't play in the end, Allen... they've got a lot of mobile players who can hurt you. We wanted to keep the game in front of us which we did very well, and sometimes that means you have to concede more possession than you might like.
"We probably didn't risk the ball enough in the second half, when you're put in a bit you need to be really brave to play through them, we had our moments but not enough."