However - despite scoring in each of his opening two Premier League fixtures - Rooney's performances have certainly been lacking and the 31-year-old attacker is in danger of being dropped ahead of Sunday's return to Old Trafford.
He spent 13 years at United, and was its most recent captain and all-time record scorer with 253.
Everton have struggled to score goals without the Belgium worldwide, with their two in four Premier League games both having been scored by Rooney.
"I hope the stadium will show him the respect he deserves before and after the match, not during the match", the United boss added.
"I think sometimes the word "legend" is used too easily but that's not this case".
'I will have a meeting with most of the players - with the key players, ' said Koeman, whose side travel to Old Trafford on Sunday for a reunion with Romelu Lukaku.
"(But) he's an Everton player, he's one of the players who needs to react and to bring the level that we expect from players like Wayne".
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"But United are a stronger team than last season and at the moment we aren't at the level we were last season".
"He is clearly a player who has adapted to the Premier League".
"It's a good question to the manager, because I asked myself the question 'what am I doing wrong?' about the second half against Tottenham, and the first half, because it's the way I like to see my team".
That, for Ronald Koeman, was the last straw and will now speak to his players about their extreme drop in form this season.
"They're waiting for a real chance to start matches and to play from the beginning". He has good friends already in the dressing room, and has had an easy integration into our group.
Rooney, who since returning to Merseyside has retired from global football, is also the highest scorer in United's history and this Sunday returns to the club where he scored a record 253 goals in 559 appearances. Rooney despite what many have said is still probably our most unsafe goal threat but the one big change that needs to happen is that Calvert-Lewin needs to start.
"I have the experience - we had a bad run last season, I had a bad run with Southampton, we came out of those", he stressed.