Eaves, a target man similar to Revell, arrived at New York on Saturday morning on an emergency loan from Bolton and came on as a substitute in the 1-1 draw at Walsall.
Revell, who won the club's player of the season award last term, has been a stellar performer in the opening weeks of the campaign and Evans insists Eaves is at the Millers to help ease the workload.
"Revell has been absolutely fantastic for us," he said. " But it would have been unlikely for us to get him 55 games in a season.
"But how good has he been, he has been the first name opposition managers have mentioned after the games.
"But we have found someone who can play with him and can do a similar job to him if we need to pull him out.
"The time to strengthen is when you are strong. If you try and strengthen when you are weak you get the bottom of the barrel.
"It's been a good time to go and get Tom Eaves, we're fifth in League One and unbeaten in 13 games."