Evans, whose side led up until that point courtesy of Joe Skarz's first-half goal, was left seething after 71 minutes when his skipper Craig Morgan received a straight red card for his tackle on Callum Wilson and Coventry captain Carl Baker equalised from the resulting spot-kick.
Following the 3-1 home defeat, Evans said: "This is one of the worst decisions ever given in football by an assistant referee. The offence occurred outside the D on the edge of the area, this isn't on the line. The man should never officiate again.
"The referee gives a free-kick but then gets sucked in by his assistant. It's a poor decision that changed the game."
Franck Moussa then headed in Baker's corner to give the visitors the lead but Rotherham threw away the chance to rescue a point when Michael O'Connor's injury-time penalty was saved by Joe Murphy.
And with the Millers goalkeeper pushed up as they searched for an equaliser, Baker fired in Coventry's third goal from the halfway line in the 14th minute of added time.
Evans added: "We are not going to cover anything because we could have had the game wrapped up by half time, but we didn't put our chances away and we had four or five good chances. But we didn't make a chance in the second half.
"But it was just a shocking, shocking, bad, bad, decision for their penalty. We have just looked at it again in the dressing room and the players are appalled.
"We accept the red card but to get a penalty against us as well. The assistant referee should never officiate again at this level that decision was so bad."