Curtis Morrison and Ricky German scored for the Spireites but their efforts were cancelled out by strikes from Millers players Chris Dawson, Joshua Kayode and Kuda Muskwe.
“I was very pleased with the majority of the performance,” Humphreys said. “The young players we had really applied themselves and took the messages that myself and Dylan Kerr were giving to them on board really well.
“It was just in the latter stages of the game where we switched off from a corner for us, which allowed them to break and score and then from a corner against us.
“So overall they didn’t deserve to lose the game and there’s lots of aspects we can speak to the players about and help to bring them on.”
Under the terms of his loan agreement with Matlock Town, Morrison is still eligible to play for the reserves, and Humphreys was delighted to have him at his disposal.
He said: “I was really impressed with him, he worked tremendously hard and scored with a great finish.
“And then for our second, he recovered a ball which he had no right to recover, got himself on the counter attack into the penalty area and squared it for Ricky to score.”
Another positive from the game was that defender Paul McGinn completed 60 minutes unscathed following a spell on the side-lines with a hamstring injury.
“Paul got through an hour, and was excellent in his time on the pitch, so that’s really good progress for him,” Humphreys said.
“He had more touches on the ball, overlaps, crosses while he defended well in one on one situations.
“Whenever you get someone senior in like Paul with a younger group, it’s fantastic when they lead the way and the young players follow.
After a busy few weeks, the reserves now only have two matches remaining, both of which are at home against Mansfield Town on March 21, and Hartlepool United on March 28.
Given the first team’s hectic schedule during the same period, the recent reserves fixtures have been played members of the youth team, and Humphreys will look to blood members of Kerr’s team in the final games where possible.
And who knows? Maybe some will end up involved in the first team squad like Joe Rowley.
Humphreys added: “There may be times where we need senior players to get a game, so it’s always a case of seeing who needs what.
“But it’s nice to have that continuation of the youth team players coming into the reserves and playing with the professionals. In the few games that we have remaining we’ll look to keep it going.
“We’ve seen that the manager has put Joe onto the first team bench, and that’s great to see someone from the academy going through to the first team.”
Chesterfield team vs Rotherham: Parkin, McGinn, Fowler, Taylor, Hand, Lynam, Morrison, Beesley, German, Brownell, Ofoegbu.
Substitutes: Jones (gk), Phillips, Sharman, McKenna