Houllier made eight alterations from the side he started against Blackburn for the Eastlands clash which Villa lost 3-0 - including playing Delph at left-back.
It has left fans angry and venting their frustrations on message boards and radio phone-ins, particularly as local rivals Birmingham have won the Carling Cup.
Under-fire: Aston Villa fans are unhappy with Gerard Houllier's disregard for the FA Cup
But Delph believes the players left out needed to recharge their batteries and that Houllier has been consistent in his policy of changing his line-ups all season.
The former Leeds player, who signed a new four-year contract yesterday, said: 'We're a very good squad and we've got a good squad of players.
'The changes that got made, they needed to rest. They've been playing a lot of games this season.
'The players that came in against Manchester City were more than capable of doing a job.
Second best: Fabian Delph is outmuscled by Yaya Toure as Villa were outplayed by Man City
'I don't think it's a case of that we played a weakened team. We played a strong team, players that have been playing all season.
Uncomfortable: Delph was played out of position by Houllier at left-back
'The gaffer is confident in our ability and thinks we're strong as a squad.
'If he's bringing players in, which he's done all season, not just in the City game, I don't see why it should be looked upon as a bad thing.
'Let's face it, we came up against a very good team in City. All of their players are internationals. They were just the better team on the night.'
Delph added: 'I can understand the fans, because they got into thefinals and semi-finals of the two cup competitions last year. They arebound to be a bit upset.
'They're looking at the Blues as well, thinking that they've just won the Carling Cup.
'We think we are a better team than them and we obviously haven'tdone what they've done this season, so I think that's what is gettingto them the most.
'Hopefully next season we can push on anddo a lot better. The last few games we have looked a lot sharper and wehave started to play together as a team.
'If we can carry that on I think, hopefully with a few more players, it might spice it up a bit more.'
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?Explore more:People: Fabian Delph, Gerard Houllier Places: Birmingham, Leeds
Source: Daily Mail
Source: Daily Mail